My solution: If I pick the first Actor (lets call it "MHEndMover") with its tag equal to NewMonsterEnd's AttachTag and call "NewMonsterEnd.SetBase(MHEndMover)", movement work for all NewMonsterEnd again. But because this is only my guess and documentation about SetBase() is rare, I'd like to know what its does in detail. For now I've found
- wiki.beyondunreal.com: Actor Bases
- from stock code Actor.uc: the following events are probably risen after a call to SetBase(): OldAttachedActor.Detach( Actor Other ) and NewAttachedActor.Attach(Actor Other) (in this order?)