Grace m900 USB interface not receiving audio from Nuendo 8.2

My new Grace m900 USB headphone device, though recognized as the VST output device by Nuendo 8.2 does not receive audio from Nuendo. The Grace m900 is recoginzed and works with Reaper, Apple Finder, and iZotope RX6 but not Nuendo 8. Any suggestions?

Thanks,

Bill