I’ve been going through this issue in campaign since the big update has been release. I would hop into the campaign of Halo 2 anniversary, set the game up and I would notice the options for ‘visuals and music’ would be set to ‘classic’ so, I just set it to Remastered, then start the game, when the game starts, right away the cutscene would be playing in classic mode automatically even after I set it to remastered.
BTW, I’ve been noticing frame rate issues when playing splitscreen on halo 2A. Please look into that.