I have similar problem ; however, I know at least which map I am bugged on …on Frostgorge sound. I was already noticed this bug to me b4 i get close to 99%. Now I have completed all except this bugged one.
I have 100% on char on char selection but 99% on medal.
I have all vista as viewed in that map, but the map still say i am missing 1. I revisited all vista on the map but no update still.