i was playing in a semi vanilla server with no plugins that affect gameplay. i was gonna cook some iron for a pickaxe and when i put the coal and the iron, it didn't work. i tried replacing it, putting it in a different area, relogging, heck even using different furnaces. they all didn't work. i am gonna show you a video i took about this bug. https://www.youtube.com/watch?v=NsEN7Pn_gOw