Help! A Native Instruments audio interface fail

[BatBoySings]

This seems more a driver or hardware incompatibility rather than a DP bug, but here goes:

I just bought and installed a new Komplete Audio 6 USB interface. Using it with DP 9.02 on a 2015 MacBook Pro. I still use my UAD Apollo Twin Solo - works perfectly, but it's not portable like the Komplete A6.
DP has no trouble recognizing the Komplete A6. I load Kontakt 5 and Omnisphere instances; stereo output 1 sounds fine. If I use just that one stereo output, my DAW has no problem recognizing all my instruments.
But if I try to use other Kontakt or Omnisphere outputs (like "Kontakt 5-1 3-4" or "Omnisphere-1 3-4") with the Komplete A6, silence.
I switch to my laptop's Built-In Audio Output - everything works great.
I switch back to the Komplete Audio 6 - again, silence whenever I try to use an output that isn't the main one. I can't access outputs 3 through 16 of any of my VI's.
(In fact, even outputs 1-2 fall silent if I so much as route my Kontakt instrument through a single bus.)
This sucks. I'm sure there's something I can do to make it work but I have no idea what. My other interfaces don't seem to have this limitation. If I can't figure this out, I'll have to return the interface and get an Audient or something.

Anybody know what I have to do to get additional outputs to work through this interface?
Thanks very much.