Currently, the campaign themes play in the campaign selection menu, but once you select a campaign, the music fades out and doesn’t play in the mission selection menu. The campaign background also disappears and gets replaced with the default one.
I’d suggest keeping both the campaign theme and its animated background scenes playing while you’re browsing missions. These would literally just be a couple of small engine tweaks, but I think they’d do for the atmosphere.
Sometimes, it’d be nice to keep hearing Jesper Kyd’s amazing music (which is already way too underutilized in the game) while deciding which mission to play