Items wont smelt / furnaces arent working

Im currently using the newest minecraft snapshot and the furnaces wont smelt. I was trying to covert the new "raw iron" but it wouldn't smelt, the furnace wouldn't even turn on. (I tried coal, wood, charcoal, lava buckets, coal blocks) I then tried other smeltible items including raw mutton and oak logs, but those would smelt either. I even moved the furnaces and made new ones but nothing worked.