MIDI Interface Recognition in Audio MIDI Setup via RTP Network, Rather Than USB

I have an iConnectivity MIO XL MIDI interface. It allows communications with the computer via both USB and RTP Ethernet. I have successfully configured the RTP MIDI configuration for the MIO XL via Audio MIDI Setup using the MIDI Network Setup screen/dialog, such that I can send MIDI to/from the computer via the RTP network, without a USB cable. But the MIDI Studio page will not recognize the MIO XL Interface without a USB Cable also being connected. I don't see why that should be necessary, since all communications are being successfully performed via the RTP Network, without the USB connection. Is there something I'm missing, in order for the MIO XL to be shown as online and attached in the MIDI Studio Window? Thanks for any information you might be able to provide.