Mod Version:

1.12.2-3.6.1.0 (Dynamic Surroundings)
1.12.2-3.6.0.1 (OreLib)

Forge Version:

1.12.2-14.23.5.2847

Description:

Hello, I'm having a compatibility issue with the battle music and Noppes's Custom NPCs mod. You can set the NPCs to be either aggressive or neutral towards the player, and they'll attack you just like any other mob. However, the battle music doesn't play for these entities like it does with other mobs. It doesn't play when you attack them, they attack you, or they attack each other. However, when a vanilla hostile mob (such as a spider or zombie) attacks the NPC, the battle music DOES play.

I've made sure that resource pack is installed, I've turned on the battle music in the config, and I've tested it with vanilla mobs and it works perfectly fine, so I'm sure that everything else is functioning as it should. I don't have any knowledge of code, I'm not sure why these modded entities aren't detected as fighting.

This would make sense depending on how the the custom NPC mod implements their NPCs. The battle detection logic looks at class implementations rather than who is fighting who.