When playing campaign it appears there are some AI pathing issues. Started in Episode 1 where AI would not move right after the helicopter blows up. Reloading and continuing on and coming back much later appears to fix it but I found it again on episode 2 of the first campaign after you rendezvous with the party. AI just does not want to move forward and every so often Sporadic movement noted as well. I was able to note that killing the AI that appeared to be stuck moved the group forward a little but the same problem came up again and it was open field.