Ender chest animation stays open once you've opened it. The animation then only when you open it again. In other words the open/close animations are the wrong way round.
MC-70245
Ender chest stays open
Resolved
Cannot Reproduce
0
Can't replicate.
The only usual thing is when lag delays the opening of the chest, so it stays open after you've closed it. That always gets fixed by re opening it or let the chunk be unloaded though.