Hi @hencrypted ,
Thanks for letting us know. Since only the Airplay options appear, I suspect this could be an issue with the firewall blocking Roon from discovering Roon Ready devices on the network. I noticed you also have a Mac registered to your account, is the behavior the same if you try to temporarily host the Roon Server on that device by going to Roon Settings → General → Disconnect → Use this PC as Server? If the issue only occurs on the Ubuntu device, I would suggest checking the Ubuntu firewall settings, the below thread can help:
https://community.roonlabs.com/t/please-help-with-firewall-settings-on-ubuntu/228924