Ok so i was fighting the mighty enderdragon and stuff and I died. It was on realms there was 3 players in the end including me and one in the overworld. one switch was doing 3 player split screen and i got all my items in excactly the same spot and they would not get picked up.  it seems to happen when you are pillaring up the end pillars in an area so you are surrounded by blocks on the forward and left sides. I think I died from a dragon fireball. The chunk rendering was set to the maximum on switch.

recreate

1 summon in more types of items in than inventory slots you have in excactly the same area.

2 try to pick up.

3 cry