Steps to replicate:Step 1: Fill your whole inventory except for 5 slots.Step 2: Place a stack of iron blocks in the crafting table. (There will now be 6 slots empty in your inventory.)Step 3: Hold shift and click to craft all.You will now get 6 stacks of iron ingots, and 21 iron blocks will remain.Start With: 64 iron blocks = 576 iron ingots. End With: 21 iron blocks = 189 iron ingots, 6 x 64 iron ingots = 384 iron ingots. Total 573 iron ingots.Expected result would be 22 blocks should remain and the 6th stack of ingots will not be completely full. Instead, 3 iron ingots completely vanish. It's possible to lose more items (up to 8 iron ingots) based on the rounding.