Are you in USB multitracking mode? If so, then the USB 3-4 sends are already in use! As such, this toggle switch is unavailable in multitracking mode. To use it again, switch your USB mode back to stereo.
Are you in USB multitracking mode? If so, then the USB 3-4 sends are already in use! As such, this toggle switch is unavailable in multitracking mode. To use it again, switch your USB mode back to stereo.