1. Join a server.
2. Play for a bit after a restart.
3. All these bugs will eventually happen. Usually it's better directly after a restart but after 10-30 mins the items start to glitch out again. Just try rotating items often, picking them up/ dropping them on the ground, move them a lot, try to drag them from crate to crate, etc.
4. I have not found out the exact parameters, but it usually happens in places with a lot of loot like bases although I have seen it happen multiple times with normal spawns aswell.