Attach Actor to Component: Weapon loses rotation track of socket

I have a non-player character ( skeletal mesh ). I added a socket to the hand and attached a weapon to this socket using “Attach actor to component”. ( snap to target )

This works, but when the character walks the weapon sometimes cant keep up with the socket for a couple of seconds. It still moves the same speed as the charactor, but without the rotation. The weapon float in the last working position. After these seconds it catches up again. I use a lot of root motion with this character.

The strange thing is that this problem does not apear in “Simulate” Mode. I tried to disable functionality to get the source of this problem but cant find it.

Has anyone got any ideas ?