This seems to be a common problem many people have had.
Setting an AudioSource’s ignoreListenerPause or ignoreListenerVolume to true has no affect and they still get affected by changes to the AudioListener’s volume or whenever it’s paused.
Some have suggest to Play the AudioSource after setting these to true or to disable and then re-enable the AudioSource but none of these things work.
The only workaround I can think of is to put Pause sfx on a different mixer, but this should still work regardless.
AudioSource.ignoreListenerVolume doesn’t work for me either.
same, but pause works for me.