Intel Mac mini, Big Sur 11.4

After months of working just fine, the fire face suddenly won’t show up at all:  The total mix app and the Fireface Usb settings app don’t open on boot as usual. The interface doesn’t show up as a choice in Logic. If I open the Fireface USB settings, app it seems to be there, it shows up as the current interface. But in total mix a window doesn’t open, and if I open one manually there is no device listed in the choose a device box.

If I look at the USB page of the system report, I see it listed there. (though that seems to happen only intermittently).

I have toggled the PC/Mac mode several times. I have reinstalled the drivers. I have zapped pram and smc. I have tried all combination of power up/boot.

I’m running out of ideas! Any suggestions anyone? thanks.