This is a problem I've noted on the server I'm playing on.
There are chances that when someone dies and they go to pick up their inventory, they cannot pick any of the items up. Other players also cannot pick the items up and they just stay there until they despawn.
I too encountered this issue on a server running release 1.14.1. I fell down to layer 11 (was mining a vertical shaft, 1x2 blocks wide and had made a tower of scaffolding to climb up and slipped as I was climbing) as I died, and went to hit respawn, it appeared that the chunk was "unloaded" and the entities of my items fell through into the void. However, when I respawned and went back to the place where I died (climbed down the scaffolding) I couldn't pick the items back up at all. The entities moved as normal when I tried pushing them with water, and breaking blocks around them to reach them (in case they were actually glitched through the wall). I disconnected and reconnected to the server, and still couldn't pick them up.