Yamaha AG03 problems recording mic in Cubase

Hi, I’m by no means an expert when it comes to computer audio or Cubase so any help or advice really would be appreciated.
I’ve been using a Yamaha AG03 mixer to record vocals (only vocals) in Cubase 10 PRO with no problems.
I recently changed computer, so downloaded Cubase and installed it. Now, when I select the Yamaha mixer in studio set up, the microphone quality is appalling - much like a poor telephone line.
The mic (via the Yamaha mixer) seems to sound fine when I record it into an audio editing program (Audition / Audacity) but not in Cubase. I’ve downloaded and installed the recommended driver and have tried changing the settings on the mixer but no improvement. Presumably I’m doing something wrong, but I really don’t know what!

If you can help at all, it really would be a great help.
Thanks., in anticipation!