Magma cubes' sounds

Here's summary of a bug I'm having

What I expected to happen was...:
Magma cubes are silenced when hostile creatures branch set to off

What actually happened was...:
They get silenced only when I change the volume of the friendly creatures branch (as I know they aren't friendly)

Steps to Reproduce:
1. Set volume branch of friendly creatures to off
2. You can't hear magma cubes