Furnace not working properly does not allow fuel source

Put the summary of the bug you're having here

What I expected to happen was...:
I opened the furnace and would be allowed to add fuel sorce.
And remove things
What actually happened was....
I was not allowed to put in fuel source
Or remove things
Steps to Reproduce:
1. Put a step by step guide on how to trigger the bug here
2. Open furnace
3.try to put im coal