Steps to reproduce:

1. Load the attached add-on.
2. Make sure the "Hide Paper Doll" option is disabled.
3. Give yourself an Inmate or Guard shirt from the creative inventory or via commands.
4. Equip it.
5. Start running, then open your inventory.

Observed results:
The shirt is detached from the player.

Expected results:
The shirt is not detached from the player.

Original description:
is that a bug? I create a new shirt for my map, and open self-inventory when player is running, I can see the shirt is flying out of my body, I use backbench and its plugin item wizard to make it.