(This is on a Mac but I have no reason to think it's a Mac-specific issue.)

I import a MIDI file into BIAB for chord analysis, creating several instrument tracks plus a "melody" track with the original MIDI content.

In the mixer, the volume slider has no effect on the sound level of the "melody" track, though it does on the other tracks. The slider *does* affect the visible level on that track's RGB volume meter.