The furnaces are not working

The furnaces are not functional on the bottom or left parts.

What I expected to happen was to smelt some ore and get an iron ingot.

What happened was he furnace malfunctioned and I had to destroy the furnace.

Steps to get to the bug:

1-get 8 cobblestone

2-craft a furnace

3- have something to smelt and something to smelt with

4- open the furnace and try to smelt the item

5- it doesn't work!