When i'm trying to place a campfire in pocketmine it doesn't work. I place it. See it for a few millisecond. then disappears. Is it bcz it's not implemented? Btw i am using 3.11.5 (will update to 3.12 later) Thanks
due to technical limitation, simply put you can't.Pocketmine 3.x is stuck with level db 7 so the block can not be added.Leveldb 8 has already been added to pocketmine 4.0 but it is a development build and all plugins will break un less you update yourself.So choose an option for yourself.
The current version can only load old worlds, the 4.0.0 release will be able to load worlds from the current release of Minecraft.