Food or ore cannot be altered or smelted in any way inside a furnace.

Describe what you thought should happen here
I was going to smelt some iron ore.

Describe what happened here
I couldn't put in any burning material not could I take it back out.
Steps to Reproduce:
1.Tap on furnace.
2.Insert food or ore inside.
3.Fail to take it out or smelt it.