Put the summary of the bug you're having here

Chests/enderchests/shulkerboxes got deleted from the endspwanplatform after reentering the end.

Steps to Reproduce:
1. Kill enderdragon
2. place chests/e-chests/shulkerboxes on the ends spwanplatform
3. leave game while in the end
4.leave the end
5. close game
6.enter the end
7. chests get destroyed. shulkerboxes and echests deleted