Furnaces will turn items into wrong items
Raw Porkchop is turned into Raw Salmon
Raw Beef is turned into Cooked Chicken
Raw Fish is turned into Cooked Salmon
Raw Salmon is turned into Melon
Iron Ore is turned into Stick
Note that the result is not always wrong. Raw Mutton becomes Cooked Mutton and Birch Wood becomes Charcoal.
Thank you for your report. This issue was, however, submitted earlier as MCPE-15423. Please perform a search next time to make sure your bug hasn't already been reported. The parent issue can easily be found by searching for "mcpe unresolved furnace".