Is this enough info about my situation?

Hi b,
No it's not near enough information. Some of it makes no sense when you just read it cold. But if I make assumptions I might be missing something... Let me know

The first paragraph is how you were successfully working - I assume.

The second paragraph begins by you disconnecting the working system to try a USB cable -??? To do what? I'm assuming you want to use the Motif-Rack XS as your MIDI interface? If you want to use it as an audio interface you'll need the FW16E FireWire expansion board... The Motif-Rack XS does not send audio via USB. You've been misinformed. It does MIDI only.

When you connect the Motif-Rack XS to a computer and set MIDI In/Out = USB, You can connect your keyboard's MIDI OUT to the MIDI IN jack of the Rack XS... In the DAW (Cubase), you'll see the Motif-Rack XS referred to as "Yamaha Motif-R XS-1" (port 1). You will see your external MIDI keyboard referred to as "Yamaha Motif-R XS-3" (port 3).

So in order for your keyboard to play the Rack XS, you'll need an active MIDI track to echo/Thru the signal to trigger the Motif-Rack XS; the Track Inspector should have the Motif-Rack XS port 3 as the IN, and the Motif-Rack XS port 1 as the OUT.

This will allow you hear the Motif-Rack XS through its audio outputs and headphone jack, but does not send any Audio to the computer.
Connect the analog L/R output jacks of the Rack XS to your audio interface.

Thank you for your detailed reply. I was not trying to hear audio through my USB connection to the computer, and from what you wrote, I am now reassured there's nothing wrong with my motif XS rack. I really am new!

My ultimate goal is to be able to save multi timbral Multi mode patches to the computer and use an editor program. I can't save them on my rack because the user banks are full of patches especially designed for the breath controller. I had been getting port error messages from editor and Cubase. The information you gave me will be useful and I thank you for it.