Ok so I enjoy the campaigns from time to time and just recently learned how to play them from the FAF client. It wasn't super clear to me originally and I'm probably getting something wrong when I set a game up.
I like to turtle and go up the tech tree a bit before triggering the next phase by completing whatever task the game calls for and expanding the map.
What happens for me is after a bit of gameplay, the game progresses and expands the map with all the new goals without me completing the first set of goals that would have triggered the expansion.
The default for coop is timed expansion: on.
You need to turn this off in the lobby settings.
Right on! Thanks so much!!