Furnaces in survival will not allow you to put fuel, (wood, coal, etc..) into them and are thus, unworkable.

I expected to be able to tap on the fuel input space, (the lower), and tap on the preferred fuel in my inventory to place it in the furnace.

But instead, it would not allow me to fuel or operate the furnace

1. Make furnace.
2. Add item, (cobblestone, glass, ore, etc...)
3. Attempt to tap the lower fuel space.