Pretty simple bug, and easy to reproduce.
Usually when you go into ambush stance you should be able to move 25%.
With Nakai however, you are not able to move at all, not even if you wait until next turn.
No real workaround for this.
From my perspective this seems like an easy fix. Would love to fix this before me and my friends start our multiplayer campaign, as this really makes it a lot harder to sneak up on them.