AIR had value of 1 instead of 0 in the config.

src/main/java/world/bentobox/level/config/BlockConfig.java

@@ -42,6 +42,8 @@ public class BlockConfig {
             // Update blockvalues to latest settings
             Arrays.stream(Material.values()).filter(Material::isBlock)
             .filter(m -> !m.name().startsWith("LEGACY_"))
+            .filter(m -> !m.isAir())
+            .filter(m -> !m.equals(Material.WATER))
             .forEach(m -> {
                 if (!blocks.contains(m.name(), true)) {
                     blocks.set(m.name(), 1);

src/main/resources/blockconfig.yml

@@ -673,7 +673,7 @@ blocks:
   YELLOW_WOOL: 2
   ZOMBIE_HEAD: 1
   ZOMBIE_WALL_HEAD: 1
-  AIR: 1
+  AIR: 0
   BEEHIVE: 1
   BEE_NEST: 1
   DEAD_BRAIN_CORAL: 1