I noticed this in my survival world while crafting cobblestone slabs with the stonecutter. I had an uneven amount of slabs, and once I had a stack of 63 slabs, subsequent attempts to craft more resulted in the first stack glitching and the extra slabs disappearing instead of splitting the crafted slabs between the existing stack and an empty slot (giving me a stack of 64 and a new stack of 1), thus leaving me with 63 slabs and no new stack.