How do you use Audacity to record multi-track of a live band from a QU-32?

We have a Allen Heath QU-32 which is attached to a Mac through a USB cable.

I have Core Audio and QU-32 Audio selected. The source dropdown shows channel 1 (mono) 2 (Stereo) and 3 -32 for the rest of the options.
I can select channel2 (Stereo) for the source and record just fine. But I would like to add tracks to record individual tracks as well.

What I tried was:

  • select channel 3 from source, Tracks, Add Track.
  • Go to the new track and change the label to Vocal (which is what channel 3 is…a vocal mic)

But this doesn’t seem to work. When I try to see what source track 3 is attached to, I can’t find that info.

What am I doing wrong?