That’s really interesting, my Astarion went completely immobile too, but it was in the context of combat. Just tonight in Act 2. He had the Fear spell used on him, and he ran away into a corner. After that, he was completely immobile and wouldn’t follow my party. Returning to camp didn’t help, or moving him manually etc. So I ended up hitting him with a thunderwave to get him to move. He unexpectedly flew off a ledge into a chasm. But it all worked out because I had Withers resurrect him, and then he could move like normal again. You could try killing Astarion and resurrecting him if it happens again. It worked for me.
