Wow. This was months ago, but starting to remember more now.
On the right side of the Scarlett Mix, the “full mix” level control was set to maybe mono and then I pressed a connect setting to connect two channels or something like that.
I believe the error stemmed from my misunderstanding of the Scarlett Mix interface display. All tracks seen from left to right are inputs. No outputs. The outputs are the interfaces below. So if it looks like a level meter, it’s an input. They will all go into the computer or in the case of the full mix level control, come from the computer, then back to the computer.
For others, if this doesn’t work, check your cables and connections. Possible things get yanked out. Give them all a gentle push in. Still doesn’t work, consider using another cable on the dead side or connecting the working side cable to the dead side output. Just to check it isn’t a failed cable.
I guess the lesson learned is that the error can come from so many places outside of Cubase. Mine was Scarlet Mix interface of my Scarlett 18i8.
Hope I was able to help a bit more. I didn’t realize my posting didn’t explain what I did to fix the problem. I also was not able to check my email regarding posting alerts here. Hence the long delay for response. Both my bad. I shall be more attentive.
I appreciate this being brought up. Thanks Bedawan and apologies to all.