You would only see the hugo via USB as it only then becomes the audio device the BDP's firmware is communicating with. When your using BNC and/or AES/EBU the firmware uses the Bryston IAD (which isn't shown) not a the Hugo. My recommendation would be to unplug the hugo, turn the BDP off, back on, wait for it to boot and see if the Bryston IAD then shows under audio devices. If it doesn't you could open the unit and see if its not something simple like a loose connection, otherwise you should have the unit serviced. If the Bryston IAD does show when the BNC and AES/EBU aren't being used, but disappear when they are being used you may want to test either a different cable or dac if available, otherwise you should have the unit sent in for service and it can be tested with a BDA-2 or 3.
Chris