Hello!
there is 2 reasons I can think of where an attach could fail:
- you try to attach a static object to a movable object
- the 2 objects you try to attach together don’t belong to the same sublevel
But you should have an error in the logs, is that the case?
If not, are you sure they are not attached? You fly back the lock to the backpack, that mean you temporarily control the lock’s transform. Are you sur this code is stopped once the lock is back in place? If not the attach could have worked but if you’re still updating the actor’s transform it will look like the attach failed