Whenever I try to join a party from the mission menu, it would say that "An unexpected error has occurred on the server" and I'd go nowhere. Being forced to solo isn't fun. :c
Try starting a party and then inviting folks. That's the only way to do co-op missions I've found so far.
Try starting a party and then inviting folks. That's the only way to do co-op missions I've found so far.