Have you tried using a scene component? When ever I want to something to snap in a place I always use a scene component. Maybe for the Right Arm Box instead of using get world transform you could try this “Get Relative Location” and “Get Relative Rotation” then you could plug it into the “Set actor location and rotation.” Also you could try to make another custom event called Attach for when the arm goes into the collision box it will fire the custom event and snap into place. The detach custom event maybe causing the problem.