In campaign mode, the battle music will usually play as expected, it will play whenever creatures have engaged an enemy in battle, before going back to the normal ambient music once the fight is over.
In skirmish and scenario modes however, something strange happens. Once my creatures engage an enemy (usually neutral heroes), the battle music will play as usual. Once the fight is over, it goes back to the normal ambient music. But after that, no matter how many battles creatures go into, the battle music no longer plays and it usually ends with the large battles with nothing but the ambient music playing and not really hyping up the combat.
Also, I have heard the OST, and it seems that the game will only play the Battle Medley part with the "chanting" and drums during combat, and never switch around to its other variants.
Customer support service by UserEcho