This just happened to me in 17w07a in survival mode. I was riding a saddled horse, logged out, and the horse was gone when I logged in again. This bug needs to be reopened.
Anthony, please carefully examine the status, resolution and fix version of this bug.
Slimes have the same white/blank texture when they die.
I noticed the same in single player mode. Three dungeons, no chests.
@Andy Purnell According to the ticket update, the bug has been fixed in code. However, the new snapshot with the updated code has not yet been released, so you are still using the existing snapshot with the bug. You should see the fix when the next snapshot arrives.
I was a bit upset when I first encountered this bug, but my thought process has been changing. There is little harm in losing a few drops, and the game is more dynamic (and slightly more interesting) when I find those loose ores laying around in unexpected places. I know the game isn't intended to mimic real life, but it is worth noting that in real-life mining operation, a bit of loss can be expected. I certainly don't think that this is a big enough problem to cause people to quit playing. If this bug is marked as won't-fix and flying ores become the new normal, it's not a big deal.