usb interface of the qc suddenly stopped working

CorOS Version: 2.0.3

Describe your issue:
I have a big problem. My QC won’t show up as a usb interface. On the QC in I/O settings the usb port is/becomes (if I plug it into a pc) white (so it should have a connection), but no PC/Mac iPad shows it as an audio output/input option.
I tried different cables, shutting it down and unplugging the power and restarting it with the usb plugged in, but nothing works.
It worked fine yesterday, but now I’m not able to use it as an interface. Everything else works fine, but I depend on the QC as my main audio interface for recording guitars.

I would definitely email so they can log the issue and provide resolution.
Lastly, you might try backing up the QC, perform a factory reset and restore your backup.