Was attempting to use the Campaign Matchmaking System and the game ported me back to the start of the game. I can’t fast travel anywhere, even though I just finished Athena.
I sort of had a related issue as well. I started a solo campaign, then went into a co-op campaign with my friends, but when I went back to my solo game, everything was overwritten on my character from the co-op game.
Also looks like all my progress is gone. Game is making me redo all the missions I have completed.