Game will randomly stop playing music or sound effects, both in cutscenes and during battle.
I was recently doing Extra Story - EX05 Inscription of Labyrinth and it had sounds constantly breaking, Voodoo boss in EX05-11 made no sounds at all, I looked up an older YouTube video of the fight and the boss was making all kinds of noises.
This is very common in a lot of older content where there is silence or character art disappearing.