The pocket slot appears to be broken on-login. If I equip something like an Enchanted Gem on RS3, the dev kit will return valid bounds. If I relog with it equipped, on login the bounds will stay null until I re-equip. The Equipment slot also returns null in the Dev Kit, even if the bounds aren't null. To re-produce: Equip something in the Pocket Slot (eg Enchanted Gem), re-log, and check the Dev Kit for bounds.