Furnace glitch

Put the summary of the bug you're having here

What I expected to happen was...: I could put stuff in the bottom of a furnace
Describe what you thought should happen here
I should have been able to put flamable stuff in the bottom of a furnace
*What actually happened was...:*furnace is broken (bottom slot)
Describe what happened here

Steps to Reproduce:
1. Put a step by step guide on how to trigger the bug here
2. ...open a furnace
3. ...try to put coal/wood items in it