DigiOne Signature 'Volume is is Fixed'

I’ve lost volume control via the Roon app.
Even though Volume Control is set to Device Volume, in the app I get the ‘Volume control is Fixed’ text instead of a volume slider.
I set up the unit last week and the controls were available; they disappeared two days ago.
Can anyone assist?

PS For reference: Router - ethernet - digione - coax - RME ADI-2 DAC - headphones or amp.

Hi Michael- this is the way I understand it:

The DigiOne is sending a PCM S/PDIF signal to your DAC, there is no provision for volume in a PCM stream. You can use Roon’s DSP and adjust the volume from there, but as far as I know, not through the traditional volume control. A better approach may be to control volume after conversion to analog.

The Allo ships with Shairport enabled, which provides AirPlay compatibility. Maybe you were connecting to the Shairport “device” previously which does allow volume control?

Thanks Steve.
What’s odd is that when I first connected the DigiOne, I had the option to control volume from the Roon app.
I can control volume through the app using DSP but I lose some quality.
It’s also worth noting that my Bluesound Node also switched to fixed volume at the same time.
I’ve resolved that by toggling a control using the Bluesound app but no such luck with the DigiOne (which is otherwise terrific).
Re: Airplay I didn’t have it enabled (I’m on Windows + Android) so no joy there.