Just download digital copy of game, try a couple of missions and find strange issue.
At the beginning of Requem mission after the cutscene with Cortana i go to pause menu and after that music is dissapear, but only the music of crashsite.
I reload the mission and after the cutscene there is no music anymore.
I delete save file, start the mission, skip cutscene - still no music.
I delete save file, start the mission, watch cutscene - music is allright until i go to pause menu.
Sorry for my english.
Hope you will fix this.