Question

Cubase works fine, but normal computer sound does not play or register on the levels.  Just have usb-c wired in, and output via headphone jack.  Shouldn't this work?

Answer 1

If you are working on Windows, it may be a case of different sample rates in the DAW and Windows audio.
Check in your Windows audio settings whether the sample rate and bit depth in your windows audio settings is same as what you have in the DAW.