I had this issue in Act 1. I just ploughed on, and the condition vanished when I moved to act 2. If you're near the end of act 2, you can possibly just carry on and see if you can shake the condition as you move on to Baldur's Gate from the Shadow Cursed Lands.
But definitely report the issue to Larian, too, if you haven't. There do seem to be a number of oddities with the way the game is handling NPCs who are designated "guards", and hopefully these will be properly fixed at some point.
Happy to report this was the case. I've reported the issue to Larian all the same, but besides having to leave one plot thread unresolved due to it being the crux of the issue, moving on to the next act has wiped the proverbial slate clean.
Thanks for the suggestion. On to Baldur's Gate I go!
