Multiplayer steam seamless travel problem

Hey,
I have a Lobby where Clients could join and that works Gold
But if i travel to another map only the host is traveling. The Client gets a fatal error and the game is crashing.
Seamless travel is checked and in the logs i can see that the transition Map works on Client also the New map is Start loading. The fatal error dort leaves any Informations why Its crashing.

I have a Lobby and a Gameplay gamemode. To switch between controllers and stuff iam using Tick event from Level BP in the New map and I Check if the Controller is local if so i Fire a custom event to spawn and posses the Player.
What could It be that the Client crashes?

It was cause of get network Players Note on begin play in Level blueprint