This should fix the stone block issue.
Its recommended to backup your structure files before converting them
Use this command to convert a structure file
/is admin structure convert namehere.structure
# Fixed mobs naturally spawning at an island when the 'NaturalMobSpawning' setting is disabled.
# Fixed pig entity having no AI for the default structure file by replacing it with a new one.
# Fixed IAE when saving a structure with an enderman entity in the selected area.
# Fixed NSME when pasting a structure with skulls on 1.8-1.9 server versions.
# Fixed sound not being sent to the player being promoted or the promoter.
# Fixed blocks not spreading when 'FireSpread' setting is disabled.
# Fixed spelling mistake for a comment in the 'config.yml' file.
# Fixed NPE when demoting an offline member.
# Changed the option 'Extent' to 'Extend' for the path 'Island.Block.Piston.Connected' in the configuration file because of a mistake.
# Changed the options in the path 'Island.Block.Piston.Connected' to true in the configuration file.
# Added a notice message to the structure file option for the 'Structure Editor' menu when selecting a structure to inform server owners that the structure file must be set for all worlds.
# Added the method 'SkyBlockAPI.getIslandManager()' that returns the IslandManager implementation.
# Added the method 'SkyBlockAPI.getBiomeManager()' that returns the BiomeManager implementation.
# Added the method 'SkyBlockAPI.getLevellingManager()' that returns the LevellingManager implementation.
# Added the method 'SkyBlockAPI.getStructureManager()' that returns the StructureManager implementation.
# Added the method 'IslandManager#removeCoopPlayersAtIsland(Island)' to remove coop players occupying an island.
# Added the method 'IslandManager#getIslands()' to the API to return a list of loaded islands.
# Added the method 'IslandManager#resetIsland(Island)' to the API to reset an island.
# Added the method 'Island#isLoaded()' to the API to check if an island is loaded.
# Added the method 'Island#load()' to the API to load an island if unloaded.
# Added the method 'Island#unload()' to the API to unload an island if loaded.
# Fixed the promotion message not being sent to island members when a member of the island has been promoted.
# Fixed mobs naturally spawning at an island when the 'Natural Mob Spawning' setting is disabled.
# Fixed NPE when deleting a players island when performing the command '/island admin delete'.
# Fixed player not being removed from members list when being promoted.
# Changed the method 'IslandManager#getIsland()' from the argument 'org.bukkit.entity.Player' to 'org.bukkit.OfflinePlayer'.
# Fixed player not being removed from coop players when disconnecting from the server when the option 'Island.Coop.Unload' is enabled in the configuration file.
# Fixed World Border being sent to players that are in the nether world when the server version is 1.8-1.12 due to a minecraft client bug (https://bugs.mojang.com/browse/MC-99544).
# Fixed being able to delete the island that has the main spawn point set at with the command '/island admin delete'.
# Fixed the scoreboard glitching for other members when a member of the island disconnects from the server.
# Fixed SOFE when getting the level of an island using the API.
# Improve performance by decreasing memory usage for loaded and unloaded islands.
# Changed location and name of a few classes for the API to be better structured.
# Added the option 'Deletion Cost' to the 'Structure Editor' menu to set the cost of deleting an island that was created from a certain structure.
# Added the event 'PlayerWithdrawMoneyEvent' to the API that is called when a withdrawal takes place.
# Fixed spam in the console caused from fetching user information when the plugin cannot contact Mojang's public API.
# Fixed not being able to set a one decimal number for an upgrade cost.
# Changed the path 'Island.Ownership.Cooldown' to 'Island.Ownership.Cooldown.Time' in the configuration file.
# Changed the path 'Island.Levelling.Cooldown' to 'Island.Levelling.Cooldown.Time' in the configuration file.
# Changed the path 'Island.Biome.Cooldown' to 'Island.Biome.Cooldown.Time' in the configuration file.
# Improved performance when a player disconnects from the server.
# Added the option 'Island.Block.Level.Enable' to the configuration file. When this option is enabled, any changes to a block will be made to the levelling materials calculated for an island.
# Added the option 'Island.Join.Island' to the configuration file to teleport the player to their island spawn point when they join the server.
# Added the option 'Island.Join.Spawn' to the configuration file to teleport the player to the main spawn point when they join the server.
# Fixed a space between the prefix and suffix when using the placeholder 'skyblock_island_level_formatted'.
# Fixed the placeholder '%end_file' not being replaced for the 'Structure Editor' menu.
# Fixed NPE when teleporting to an island the player is banned from.
# Changed a few comments in the configuration file.
# Added the option 'Island.KeepInventoryOnDeath.Enable' to prevent players losing items on death when the 'KeepItemsOnDeath' setting is disabled in the configuration file.
# Added the option 'Island.Damage.Enable' to enable/disable damage when the 'Damage' setting is disabled in the configuration file.
# Added the option 'Island.PvP.Enable' to enable/disable pvp when the 'PvP' setting is disabled in the configuration file.
# Added support for LeaderHeads for the level and votes leaderboard.
# Added the method 'SkyBlockAPI.getIslandAtLocation(org.bukkit.Location)' to the API.
# Fixed the island location being set to the wrong path when setting the island location through the API.
# Fixed placeholders for messages in menus not working when adding the character '#' after it.
# Fixed the 'Loot Drops' upgrade not working correctly when having a drop multiplier plugin.
# Fixed NPE when teleporting to another island straight after deleting yours.
# Fixed being able to delete an island the main spawn point is set at.
# Fixed NPE when saving a structure with jukeboxes that don't have a record playing.
# Fixed NPE when saving a structure with spawners that don't have a spawner type.
# Changed the nextAvailableLocation being set in the 'config.yml' file. The nextAvailableLocation's are now set in the 'worlds.yml' file.
# Changed a few comments in the configuration file for the path 'Island.Settings'.
# Added the User Cache system that caches all players UUID's to a file and keeps a record of their username to prevent issues when a user expires in the 'usercache.json' file in the server directory.
# Added the option 'Island.Block.EndFrame' that allows players to pick up end frames at an island when they have the 'Destroy' permission.
# Added the placeholder 'skyblock_island_level_formatted' that returns the island level with a suffix.
# Added the permission node 'skyblock.fly.*' that gives permission to fly at any island.
# Added the method `SkyBlockAPI.giveFly(player, island)` to the API.
# Fixed NPE when a generator is added that doesn't have a name.
# Changed the permission node 'skyblock.fly' to only allow players to fly at their island.
# Changed the path 'Island.Obsidian' to 'Island.Block.Obsidian' in the configuration file.
# Fixed removal of spawn protection at an island causing a 1.13 server to crash.
# Fixed invitation message not creating a new line when using the string '\n'.
# Fixed NSME when pasting a structure on island creation for 1.13.1 servers.
# Fixed IOOBE when items are set in a container at a slot greater than the container size.
# Fixed NPE when a flower pot is placed without content when a structure is pasted on island creation.
# Fixed NPE when saving a structure with flower pots for 1.10-1.12 servers
# Fixed NSME when a flower pot is placed when a structure is pasted on island creation.
# Fixed permission message being sent to a player when they feed a pig with baked or poisonous potatoes when 'AnimalTaming' setting is disabled.
# Fixed permission message being sent to a player when they feed a wolf with cod when 'AnimalTaming' setting is disabled.
# Fixed players being able to feed ocelots with raw salmon, tropical fish, puffer fish when 'AnimalTaming' setting is disabled on 1.13 servers.
# Fixed players being able to feed chickens with beetroot seeds when 'AnimalTaming' setting is disabled.
# Fixed players being able to feed turtles when 'AnimalTaming' setting is disabled.
# Fixed players being able to feed llamas when 'AnimalTaming' setting is disabled.
# Fixed the structure tool selection not working since build 50.
# Fixed events not being unregistered when reloading the plugin.
# Added The End island world - Can be visited by entering an end portal at an island.
# Added the path 'Island.World.End' to the configuration file.
# Added the option 'Island.<world_environment>.Liquid.Lava' to the configuration file to enable lava world rather than water world.
# Added the option to the 'Structure Creator' menu to set the structure file for the end island.
# Added a few methods to the API to check if a player or location is at an island.
# Fixed players being unable to player dispensers or sticky pistons at a certain radius when the option 'Island.WorldBorder.Block' in the configuration file is enabled.
# Fixed visitors being teleported to the main spawn point rather than the visitor spawn point when they go outside an island.
# Fixed world border not being sent to the player when they're in a different world to the overworld.
# Fixed NPE when calling an island that hasn't loaded yet after changing the name of an island world.
# Fixed player not being give island cosmetics when they're a different world to the overworld.
# Fixed visitors being teleported to the main spawn point when they go through a portal.
# Fixed blocks being destroyed by fire when the 'FireSpread' setting is disabled.
# Fixed fire spread when the 'FireSpread' setting is disabled.
# Changed the path 'Island.World' in the language file.
# Made a few changes to the API - Take a look at the repository on GitLab.
# Improved a lot of code to do with the island worlds.
# The PAPI expansion has been approved on eCloud.
# Fixed members of an island not being teleported to the main spawn point on island deletion.
# Fixed members of an island not having the scoreboard updated on island deletion.
# Fixed permission status of generators being reset when reloading/restarting the server.
# Fixed the string '\n' not creating a new line for messages in the language file.
# Fixed variable being added to the end of confirmation and cancellation messages.
# Fixed NPE when the weather type of the island is null or cannot be found.
# Made improvements to the scoreboard to prevent possible bugs.
# Added the option 'Island.Portal.Island' to the configuration file to teleport the player to the end or nether world rather than the island world when they enter a portal at their island.
# Added the option 'Island.Void.Teleport.Island' to the configuration file that teleports the player to either the main or island spawn point when the player falls into the void.
# Added the path 'Island.Portal.Destination.Message' to the configuration file that sends a message to the player if there's no world available when entering a portal.
# Added a check to the confirmation command when a player wants to delete their island that requires their island to be closed.
# Added the variable '%owner' for the player head display names in the leader board menu.
# Added the alias '/island upgrades' to the command '/island upgrade'.
# Fixed upgrades now being removed from a player when they die at an island and are teleported to the main spawn point rather than the island spawn point.
# Fixed players being able to place hanging entities at an island when the setting 'EntityPlacement' is enabled.
# Fixed TNT damaging players or entities when the 'Explosion Damage' setting is set to false.
# Fixed scoreboard glitching when deleting an island.
# Fixed TNT damage destroying hanging entities.
# Change the 'ArmorStandPlacement' setting to 'EntityPlacement'.
# Removed the check that prevents the main spawn point being set in an island world. Keep in mind this will cause issues if the island you have set the main spawn point at doesn't exist.
# Added the permission node 'skyblock.fly' that gives a player permission to fly when they enter an island.
# Added a cooldown for transferring island ownership to prevent unnecessary spam from players.
# Added the option 'Island.Ownership.Cooldown' to change the cooldown time when island ownership is transferred.
# Added the line breaker '\n' to messages in the 'language.yml' file.
# Added the alias '/island explore' to the command '/island visit'.
# Added exit item to the 'Island Ownership' menu.
# Fixed the scoreboard showing no color code for the suffix when the display line is equaled to 16 characters.
# Fixed format codes not showing color code when the display line is over 16 characters for the scoreboard.
# Fixed possible fall damage when teleporting to an island spawn point or main spawn point.
# Fixed levelling cooldown not being stopped when an island is removed.
# Changed argument to a method for transferring ownership in the API.
# Added the permission note 'skyblock.bypass.cooldown' to bypass the biome, island creation, or island deletion cooldown timer.
# Confirmation Messages are now configurable in the 'language.yml' file. Use the variable '%confirm' to add clickable message.
# Cancellation Messages are now configurable in the 'language.yml' file. Use the variable '%cancel' to add clickable message.
# Added placeholder support to chat component messages (Confirmation and Cancellation Messages).
# Fixed the border not being removed when visiting another players island from your island or another players island when their border is disabled.
# Fixed cobblestone generators not generating cobblestone when a player doesn't have permission to use any generators.
# Fixed the scoreboard not being initialized when re-enabled in the configuration file when using the command '/island admin reload'.
# Fixed levelling materials not being reloaded when using the command '/island admin reload'.
# Fixed generators not being reloaded when using the command '/island admin reload'.
# Corrected the info message for the command '/island admin removeupgrade'.
# Added the console or player command '/island admin addupgrade' to add an upgrade to a players island.
# Added the console or player command '/island admin removeupgrade' to remove an upgrade from a players island.
# Added the variable '%island_points' for the scoreboard.
# Fixed island-data not saving before transferring island ownership resulting in the islands data being removed.
# Fixed the command '/island admin setsize' setting the size of an island if the island data doesn't exist.
# Fixed IAE when saving a structure with an enderman entity.
# Added the command '/island value' to get the value (points) earned from a material in the players hand.
# Added the permission note 'skyblock.value' to perform the command '/island value'.
# Added the configurable option 'Island.Settings.Hunger' to enable/disable the 'Hunger' setting in the 'Island Settings' menu (Disabled by default).
# Added the 'Hunger' setting to the 'Island Settings' menu.
# Added the placeholder 'skyblock_island_invites' to get the active number of invites for the island.
# Added the placeholder 'skyblock_island_coops' to get the number of cooped players at the island.
# Added the placeholder 'skyblock_island_coops_total' to get the number of cooped players.
# Added economy support for Coins (https://www.spigotmc.org/resources/coins-1-8-x-1-12-x-mysql-sqlite-api.48536/).
# Fixed being able to go further than the end index of the help command pages.
# Fixed new settings being set to false when being added to the island.
# Added the 'Island Border' menu for the island operators or owners to toggle the border or change the color of the border.
# Added the command '/island border' to open the 'Island Border' menu.
# Added the setting 'Border' to the Operator role.
# Added the option 'Island.Obsidian.Enable' to the configuration file to allow players to right-click obsidian with a bucket to become a lava bucket (This option is by default disabled).
# Added the alias '/island warp' to the command '/island teleport'.
# Added the alias '/island warps' to the command '/island visit'.
# Added the events 'PlayerIslandChatEvent', 'PlayerIslandChatSwitchEvent', 'PlayerIslandEnterEvent', 'PlayerIslandExitEvent', 'PlayerIslandJoinEvent', 'PlayerIslandLeaveEvent', 'PlayerIslandSwitchEvent', 'IslandInviteEvent', 'IslandKickEvent', and 'IslandUpgradeEvent' to the API.
# Fixed fly being disabled when a player teleports at a location inside the islands radius.
# Fixed players being able to use buckets at an island when they don't have permission to.
# Fixed cooped players being removed from the island when there no operator or owner is online.
# Fixed island unloading when there are no members occupying the island by cooped players.
# Fixed border of another island being sent to a visitor that isn't occupying the island.
# Fixed NSME when spawning an entity at a structure on island creation for 1.9 servers.
# Fixed visitors teleporting to the Main spawnpoint rather than the Visitor spawn point when they fall into the void at an island.
# Fixed NPE when performing the command '/island coop' if the player doesn't have permission.
# Fixed player not being removed from island when they leave the team.
# An API has been added to the plugin for developers. Please take a look at the GitLab repository.
# Fixed the leaderboard placeholders for PlaceholderAPI not working.
# Added tab completion to the commands '/island leaderboard', '/island setspawn', '/island sethologram', and '/island removehologram'.
# Added the placeholder '%safety' to the Visit and Information menu to show if an island is safe for visitors.
# Added the setting 'ExperienceOrbPickup' to the roles Visitor, Member, and Coop.
# Added the option 'Island.Settings.KeepItemsOnDeath' to the configuration file.
# Added the option 'Island.Settings.Damage' to the configuration file.
# Added the option 'Island.Settings.PvP' to the configuration file.
# Added the setting 'Damage' to the 'Island Settings' menu.
# Added coop role to the 'Settings Editor' menu.
# Fixed creation message being sent to the player on island creation when the error message is sent when the main spawn point hasn't been set.
# Fixed new comments not being set in the configuration file (New comments however will appear at the end of a path).
# Fixed the permission note 'skyblock.information' not working for the command '/island information'.
# Fixed projectiles launched by players damaging entities when the setting 'MobHurting' is disabled.
# Fixed players being able to tame entities at an island when the setting 'MobTaming' is disabled.
# Fixed NPE generated by cobblestone generators when the index for the random material is zero.
# Fixed some water problems with the ore generators caused by water physics.
# Fixed '/island chat' enabling chat for other players on the island team.
# Fixed messages not being translated when island chat is enabled.
# Fixed custom entities not spawning in the island worlds.
# Fixed projectiles being under the wrong setting.
# Fixed a few mistakes in the 'language.yml' file.
# Recoded the 'Settings Editor' menu.
# Added Console support to the command '/island admin delete', '/island admin owner', '/island admin reload', '/island admin removehologram', and '/island admin setsize'.
# Added a check when creating an island that checks if the spawn point has been set and if not an error message will be sent to the player.
# Added the setting 'ArmorStandPlacement' to the roles Visitor, Member, and Coop.
# Added the option to the configuration file to disable Island Coop.
# Added 'Coop Settings' to the 'Settings' menu.
# Added the setting 'Edit Coop Settings' to the 'Operator Settings' menu.
# Fixed players inventory not updating when interating with an item that is cancelled at an island if the player doesn't have permission.
# Fixed cobblestone generators not forming cobblestone when there are no generators or no materials in a generator.
# Fixed island operators being able to edit the island settings when they permission for that to do so has been disabled.
# Fixed NPE when a player doesn't have permission to change the permission of a setting when they've been removed access.
# Fixed the command '/island admin setsize' setting the size of the senders island when the target player is online.
# Fixed the command '/island admin owner' getting the island owner of the sender when the target player is online.
# Fixed the command '/island admin delete' deleting the senders island rather than the targets.
# Fixed NPE when a chance of a material for a generator is set to zero.
# Changed the unban item in the 'Operator Settings' menu from a name tag to a rose rose.
# Changed the setting name for 'ArmorStand' to 'ArmorStandUse'.
# Added a Coop System (Allow players to access your island even if it's closed as long as an operator or owner is online).
# Added the command '/island coop [<player>]' to open the 'Island Coop' menu or add/remove a coop player.
# Added the option to the configuration file to remove islands the player has been banned from when they open the 'Island Visit' menu.
# Added the setting 'CoopPlayers' to the 'Operator Settings' menu.
# Fixed players not being teleported from an island when the island is closed or the player has been banned from the island when they join the server at the island.
# Fixed players with bypass permission not being able to visit an Island from the 'Island Visit' menu if the island was closed after the player opened the menu.
# Fixed island time not being synchronized when a player joins the server at a loaded island.
# Fixed the 'Vote' leaderboard not showing the correct top 10 players.
# Fixed Placeholders for PlaceholderAPI returning an empty string.
# Fixed a memory leak issue when unloading islands.
# Fixed falling blocks not falling at an Island.
# Replaced statistics item in the 'Island Bans' menu with information item.
# Added Placeholder support to Essentials Chat (Requires open curly bracket and close curly bracket).
# Fixed NPE when adding Placeholders to holograms because the hologram is an world entity.
# Fixed the 'Island Visit' menu not sorting the islands correctly when changing the sort.
# Fixed the 'Vote Leaderboard' not showing the positioning the islands correctly.
# Fixed 'Next' or 'Previous' page item not working in the 'Island Visit' menu.
# Fixed the command '/island level <player>' not showing the players level.
# Fixed IOOBE when there are no tiers in the 'Upgrade Editor - Size' menu.
# Fixed players dying from the void at an Island when void teleport is enabled in the configuration file.
# Fixed Flower Pots dropping when a structure is pasted on Island creation if a block below it is air.
# Fixed Flower Pot contents not being set when a structure is pasted on Island creation.
# Fixed 'Island Upgrade' menu showing 'Jump Boost' upgrade in two inventory slots for 1.13.
# Fixed 'Island Upgrade' menu not showing the correct potion items for 1.9-1.12.
# Fixed the command '/island admin delete' performing the command '/island delete' instead.
# Fixed NPE that can occur with some Java versions when the visit-data is being loaded.
# Fixed NPE when spawning entities when a structure is pasted on Island creation.
# Fixed 'Island Visit' menu occasionally returning NPE when opening.
# Added the alias '/island leaderboard [<Level|Votes>]' to directly open a leaderboard menu.
# Fixed ban message being sent to the player when they're not at the island they've been banned from.
# Fixed a spelling mistake with a message.
# Fixed signs showing debug message.
# Added a Hologram System that can display leaderboards of top 10 level or votes.
# Added the command '/island admin sethologram' to set the location of a hologram.
# Added the command '/island admin removehologram' to remove an existing hologram.
# Added the alias '/island teleport <player>' to the command '/island visit [<player>]'.
# Added the placeholder 'skyblock_leaderboard_level_<1-10>'.
# Added the placeholder 'skyblock_leaderboard_votes_<1-10>'.
# Fixed invalid unicode character when adding color codes to signs when saving a structure.
# Fixed NSME when sending a World Border to a player on servers using 1.9 & 1.10.
# Fixed NSFE when buying 'Spawner Boost' upgrade on servers using paperclip 1.12.
# Fixed Placeholders not working for Upgrade messages.
# The command '/island admin reload' will also reload the holograms.
# Added the alias '/island teleport <player>' to the command '/island visit [<player>]'.
# Fixed NSME when sending a World Border to a player on servers using 1.9 & 1.10.
# Fixed NSFE when buying 'Spawner Boost' upgrade on servers using paperclip 1.12.
# Fixed Placeholders not working for Upgrade messages.
