So this is a pretty significant design flaw.
I approached the goblin ambush at the looted out village with the windmill gnome.
I decided to sneak Astarion in a back away and position him on a rooftop behind two goblins. I then started the encounter with the rest of my party. I was planning on having Astarion sneak up and kill a goblin to start his participation in the combat. I dispatched one, but Astarion did not enter combat. The world was still frozen around him. So I killed another. And another. As long as I killed the goblin in one hit, Astarion would not become a participant in the combat, and could walk around the frozen adversaries.
Normally with fully optional exploits my motto is if you don’t like it, don’t use it, but this is different. I want to be able to enter combat with an initial sneak attack, especially when more classes and multi-classing is added for a planned all assassin party.
I suppose I could kill one enemy and just make myself get caught, but it does kill the excitement of playing a game when you have to compensate like that for not functioning as intended, as I’m sure that this is not.