Hello @Mark_Thompson,
Thanks for contacting support, I’d be happy to take a look over this issue with you. Can you please provide a description of your setup using this link as a guide:
Please let me know what your Roon Core is and the specifications for it, what devices you have connected to it that are not showing up, and how they are connected (WiFi, USB or Ethernet). Can you also confirm that the attached devices are powered on and the correct input is selected for them prior to attempting to access them in Roon? Please let me know when possible.
Thanks,
Noris