I have another issue . . . two actually.
Every time I start to play music, i.e. a new album this volume goes to maximum on my streamer. Roon is set to Fixed Volume. I don’t want to control the volume through the Roon app as its too easy to go too loud or too quiet. My hifi has a remote control which is much better to use.
The second issue occurred as I was trying to debug the above. Roon refused to play any music and kept repeatedly skipping to the next track. Selecting a new album or playlist would also keep skipping to the next track without playing any music. I had to restart the Roon Core to stop it. After the restart, the Sonore UPnP bridge has now disappeared from Roon altogether so I am now sitting in silence. 
Just to confirm my setup is:
- Roon Core on mac mini
- Roon Player on iOS
- Sonore UPnP Bridge running on an Audiostore / Vortexbox Mite
- Streamer is a Naim NAC-N 272
- Everything is connected to router via ethernet cable (other than the iPad of course)