It seems if you have a Redstone Comparator connected to a Furnace and try to cook food it causes the menu to just close and the items in the furnace disappear [Video]: http://www.youtube.com/watch?v=lzQzIP_a39s
MC-9563
13w06a Furnace Bug
Resolved
Duplicate
0
Patrick Mitchell
(Unassigned)
Unconfirmed
Snapshot 13w06a
Retrieved
Duplicate of MC-8022, please use the search function to see if your bug has already been submitted. Currently over 51% of tickets are being closed as duplicate.