I was starting a new survival level and i found iron, so i had to put it in the furnace to smelt it and get iron

What actually happened was...:
It wouldn't let me put a fuel source in so i went to another furnace that already had coal in it and it smelted it, but i couldn't take it out.

Steps to Reproduce:
1. Open the furnace menu by clicking it.
2. try clicking the spot to place the the fuel for the things you want to cook or smelt.
3. also if you have a fuel a fuel source already you cant take the finished product out