VST Connect Focusrite Scarlett 2i2 USB problem

I’m having a problem with VST Connect Performer. The day before yesterday, a voice artist had an issue with a Focusrite Scarlett Solo (Gen2): the Focusrite interface was selected in the “Device” settings, but there was only one stereo output (L/R couldn’t be selected as mono in the monitor settings), and there was only one mic input—which wasn’t the Focusrite, but the Mac’s built-in microphone —we were able to resolve this by having the voice artist set up her “old” iMac again, and it worked on that machine.

The new voice artist has a Scarlett 2i2 USB and macOS Sonoma. She has the latest version of VST Connect Performer installed and has granted microphone permissions for Performer in the privacy settings. Unfortunately, she’s experiencing the same issue as the other voice artist did two days ago. We tried using an older version of Performer, but the same issue persists. Creating a new session on my end didn’t change anything either. What can we do?

The only options available for “Device” are “MacBook” and “Scarlett USB.” Unfortunately, switching between the two and back again doesn’t change the behavior at all.

What’s strange is that the interface’s output is active—she can hear me through the headphones.

Kind regards

input aggregate devices in midi audio setup works.