The kit room is empty
Run/perplayerkit autosetup to fill it with the bundled setup. To stock it yourself, /kit → nether star opens the editor; /kitroom takes only save and load. Shift-right-click the barrier block to save each page. Closing the menu discards it. See Set up your kit room.
Items disappear from player kits
Withitem-filter.enabled: true and kit-room-only: true, the filters loaded copies against your kit room. Stored definitions remain unchanged unless you save edits or purge them. Add the material, or set kit-room-only: false. Enchantment, potion, and other item rules still apply. See Anti-exploit.
A player’s kits vanished after they switched accounts
Kits belong to a , so a name change keeps them but a new account does not. Run/transferkits from the old account while both are online.
Kits differ between servers on the same database
Set the samekits.max-slots on every server sharing the database; a kit in slot 12 does not exist on a server capped at 9.