Nothing happens when right clicking with a diamond on the latch (it just opens the chest), both sneaking an non sneaking. I also tried aiming it at different sides of the latch. I can see the bounding box of the latch.

I'm running 1.12 now, previous ticket for 1.11: #45

This appears to be a graphical bug, You can put and diamond on the latch and take it off. It just doesn't appear. It still acts as a personal chest.

seems fine to me

Yeah, this appears to work fine.. Does logging out and logging back in show the chest as locked? I fire a packet as soon as you add the personal item..

It turned out the server I was on, was using totems of undying instead of diamonds to personalize ender chests. It works when using that. I have not gone back and tested in single player after changing the configs back to default to verify that diamonds work though.

Alright, ill close this for now then, let me know if anything changes.