The game crashed while I was completing Harbor of the Twice Drowned and my mount and thrall remained inside. After selecting another follower and mount, their status was still ‘Following’. Since then, I’ve adventured around, shut down and relaunched, and their map indicators still place them in the same spots, and their status still hasn’t changed from ‘Following’.
Is it intended that your followers have to be rescued from dungeons? If so, the crash when I was so close to clearing it couldn’t have been intended.