Character Selection is not working for Clients (Steam, UE4)

Hi! I am having an issue and i really don’t know how to fix it.
I made a multiplayer game using this series : Unreal Engine 4 Tutorial - Online Sessions Part 1: Getting Started - YouTube

I don’t know why but when i test my game with Steam, when the host launches a game, the client’s character is always de same, the default character named “thirdpersoncharacter”, and not the character who he chose in the lobby. Also, i don’t know if it’s related but when a game starts, before the player (client) joins the game, he freezes during like 4 seconds and then the game starts for him. Do you-all have any idea of what is the problem? Thanks