Roon has a very good support department. You can always contact them for Roon related issues.
Here are a few troubleshooting steps to try.
Roon Ready player (Sonore Rendu)
1. Check to make sure your DAC is working
A Rendu won’t show up in Roon unless the DAC is working. You can check on the DAC in the DAC diagnose (sonicorbiter.com → Manage → Apps → DAC diagnostic) if Your DAC is not there or has an error try rebooting you DAC and rebooting the Rendu.
2. Check to make sure the Roon Ready app is working correctly
You can do this by pressing save changes in the Roon Ready settings (sonicorbiter.com → Manage → Settings → Roon Ready)
3. Make sure your player is enable
In the Roon app go to Settings → Audio and look in the Roon Ready section. You may need to enable and name your Rendu player.
4. Select an audio Zone
You need to select your player in the Roon app before you can control it.