Music typically stops after engaging many enemies for a short duration.

For example, my wz rank 42 crusader will teleport in, ambient music plays, crusader encounters warp gate and many enemies, music elevates from ambient to battle, crusader starts doing his job, then music will stop playing.

Unfortunately, the music will not play for the rest of the mission, therefore i consider this a bug.

This consistently happens when I play high battle wz missions.  I believe you can test it by allowing many enemies on screen.

I listen to the soundtrack when not playing so this bug is especially aggravating to me.  The music is a significant part of the experience for me!

I play on Xbox One X.  Thank you!