My KANN Cube does not recognize Allo USB Audio output port

I’ve been using my older Astell & Kern AK300 and KANN portable players as DACs with my Allo USBridge Signature network player in my Roon network, but have not been able to get my new KANN Cube player to work with it.

With the older players, I just select USB Audio DAC mode and connect it to the Clean USB port on the Allo, and the player shows up in Roon’s list of audio devices (as well as the Allo device itself). However, the KANN Cube will not let me select USB Audio DAC mode unless it sees an electrically valid USB port, and the Allo’s “Clean USB” port behaves differently from an ordinary USB port on my PC, for example, for which the KANN Cube USB Audio DAC mode can be selected.

Might anyone here use Astell & Kern players as DACs or have suggestions?

Thank you!