4.15 Control rotation glitched out for client

I am currently trying to make a multiplayer shooter. I am using the Animation starter pack to get first person and third person view. I made it so, when you look down spine 1,2 and 3 are rotated so the character looks down in first and third person. The Blueprint is working for clients and server, but somehow the player arms and Gun is glitching and being teleportet back. Here is a Video, showing my problem.

And here are Screenshots from the Blueprint. I´m sorry for the mess and my bad English.