I noticed it as well, the torch seems to pick a wall and stick with it too. I've repeatedly tried to swap sides in a 1 block wide tunnel and it always placed on the left.
The progress in what you are mining/building is usually reset, so it may be some sort of chunk save problem.
The furnace is still fully usable, this bug hasn't affected the performance at all. Just how it looks.
Benjamin Aprile
I noticed it as well, the torch seems to pick a wall and stick with it too. I've repeatedly tried to swap sides in a 1 block wide tunnel and it always placed on the left.