When you pick Canah as a party member then fight his vision when he gets down to about 20% his break bar does not get reduced by the reflected grenades and he remains permanently invulnerable. The same mechanic worked twice earlier in the fight but when he starts his “flee” mechanic at low health something breaks. I’ve tried 3 times now and it’s blocking me from completing the story.
Edit: Finished it by just redoing it and just not picking Canah.