HI chesterwatson, and sorry for the delay.
once the issue came out, did you manage to solve it by reboot your unit?
Is your unit dc +usb powered or just usb powered?
you can also do a "factory" reset by holding Main output cue selector + mono while plugging DC only (first 2 buttons in the 5 buttons row under main output knob)
everything should be fine then.
best,