Not sure if this is something that’s been covered or not. I finished the game and unlocked all map/fast travel stations. I joined my brother’s game where he only had 2 of the major story fast travel places set up. When I went back to my game, I lost EVERY fast travel location that my brother didn’t have.
Also on a side note, it’s annoying that the Slaughterstar 3000 mission doesn’t have ANY sort of checkpoint system. First I got to the last wave and a guy glitched in a wall and I had to quit. Then I got to the last wave and the game crashed.