I am having a similar but not quite the same issue.
I am using a Mac controlling a Naim Uniti Atom via network.
The volume quickly jumps and skips to 100% and zero when changing volume in Audi.
SCRAED THE CRAP OUT OF MY 4 MONTH OLD BABY!!! …and me.
If I use the keyboard short cuts for volume it again skips to max output!
The min max volume control in Audi has no effect / protection.
I can change the volume manually on the atom but that defeats the purpose.
Also the audio drops out after 10-15 seconds of play.
Very very glitchy tech.
I just downloaded to trial and compare to Roon using the exact same system.
Roon is 100% stable.