I’m assuming travel to game is switching worlds? GetWorld() is a pretty safe function. Could you run it in debug with breakpoints? That’s about the only way to know the behavior.
In which function do you call TravelToGame()?
Did you change your level to use AOneVOneGameMode?
We need the code.
Seeing the callstack would also be helpful.
My guess is that your function is being called when the world is being destroyed, and the gamemode is already invalidated.