Items dropped from death sometimes can't be collected after returning to the location despite still being visually there... Some items can be recollected, other will float there and eventually expire..I've tried pushing the items into myself by building around and on them and I've tried mining under them to move them, neither has worked.

While we're on the topic of items disappearing, when planting carrots, it sometimes consumes upto 5 carrots for a single plot, and fully grown plots frequently only yield a single carrot..

So far this has caused me to lose multiple diamond and iron tools, SEVERAL stacks of torches, iron, gold, coal, and redstone, armor, and more..