Roon cannot find UPnP device (Devialet Phantom Classic)

I updated my Phantoms to DOS 2

Danny’s extension finds the Phantoms - no issues there. (However, it takes a small edit to Danny’s source code regarding the name of the Phantom - see that thread for more info)

However, the extension is only able to change the volume if the Phantoms are actively using UPNP. If playing something via the optical input, like I do with Hifiberry Digi +, the extension cannot change the volume.

For example, while playing music using Audirvana to the Phantoms, using UPNP, I can use Danny’s extension to change the volume. But If I stop that and move to playing via Roon, no more volume control.