When I tap on the furnace it isn't letting me to put any types of fuel into it, it is only letting me put stuff in it what I'm wanting to burn.

What I expected to happen was...:
I expected to be aloud to put coal into the furnace that will allow me to burn iron or any other materials that I can burn in the furnace.

What actually happened was...:
It wasn't letting me put any types of fuel into the furnace whilst I had materials in it what I was wanting to burn.

Steps to Reproduce:
1. Get stone
2. Make a furnace
3. Try and put fuel into it