Says in the name.
Whenever I switch to a character, or the character is switched whenever i'm playing this main save with friends, the game just ends up freezing on said character. I believe moves no longer work, they can't move, the game still moves, but if I try reloading a save, the screen goes to black and doesn't do anything, and the only way is to restart the game, which is a bit annoying. This issue only started when we made it to act 2, and head towards the bandit woodmill base.