I've had similar issues; I snuck up on Asterion (before the conversation/intro) pickpocket him, then unhide and the story intro started. Then, sent him to the camp and went to continue the story and the rest of the party would not follow.
If I make one the npc's leader, then only character that follows is the primary -- the rest stays put. It doesn't matter if the party is split in different ways.
a reload doesn't fix it, restart and reload doesn't fix it. An earlier save works.
I guess I will have to avoid hide with my rogue for the time being.

Last edited by wbochar; 11/07/22 02:35 PM.