Traveling between floors within the same Act sometimes causes the music to drop out while playing on the PS5. (Sfx remain). It is not 100% consistent, and it's unclear what the actual conditions are that cause it, but changing floors is always the trigger. This issue affects both single player, as well as (at least) local multiplayer.
To restore the game's soundtrack, either travel somewhere that forces the music track to change (eg. warping to/from a Gauntlet level, or entering a boss arena), or exit the game and restart it from the PS5 main menu. (If "Quitting" a game from the game menu and returning to the game's title screen, the title screen will be musicless, and reloading the game file from there does not resolve the issue.)
