How to reproduce :

1. Have a full inventory (or less) 

2. Get killed by a mob ?

3. Some items flies on the top of the ground

Description :

Sometimes, when I get killed by monsters, and when I have a full inventory or less, some items flies 2 or 3 blocks above the ground, and I can't get them back.

I tried to restart my world, and now the items are normally on the ground, it's confusing.