Thanks for the link.
You mentioned the backpack has physics simulation enabled, but I see that in your Pl_Backpack blueprint, backpack_Cube_2 which is your simulated mesh is not the root component of the blueprint. That means that the backpack mesh will move but it won’t affect the transform of your actor.
If you attach the lock back to the actor, it will be attached to the root component of your blueprint (DefaultSceneRoot). So your attach is probably successful but technically the actor doesn’t move, only the backpack mesh does.
To fix that, you can either:
- use “Attach Actor To Component” and use backpack_Cube_2 as the parent
- or in your Pl_Backpack blueprint set backpack_Cube_2 as the root component so the physics simulation can move your actor