This did not happen on this account, but to my wife and I am posting for her.
At the beginning of Chapter IV, she hit escape during a convo and it said
"You can leave now and come back later by hitting the 'play' " button.
She returned to fleet , but when hit 'play' got this message:
"The mission requires a follower that is unavailable at this time."
Her quest log is at "Speak to Koth". "reset" and "abandon" are both grey'd out.
She can travel to the planet, but no flight path or people to speak to, etc.
Her only companion is Lana ... what companion is it wanting, Koth?
Any help or suggestions?
If support does respond, can PM her account name (she is a subscriber)