Bruce, are you migrating your old Roon Core to the SGC to act as a new Roon Core? If so, have you followed these steps:
I am a fellow user and don’t use an SGC, but there may be another setting required to enable Roon on it to act as a Core. Have you also reached out to SGC, they are very helpful from what I have seen in the forum.
I ran into this problem last night when i did my upgrade. I did not follow the instructions from the SGC people exactly. I upgraded first, then I did the system upgrade. I rebooted several times but no go.
Using a web browser, go to:
sonicorbiter.com → Manage (under Music Servers, next to the sonicTransporter) → Settings → Roon Server
Make sure no checkboxes are selected and press Save Changes
I thought since the checkboxes were already unchecked that I did not need to save changes, but I was wrong. When I repeated this step and saved changes, the Core suddenly became visible.
I got it to work, no idea which steps did it but it works
== deleted all the apps on the SGC
== deleted Roon on all previous cores
== deleted and reinstalled Roon on remotes
== ran update for OS on SGC even though it was latest
== powered down SGC and restarted
== installed Roon on SGC
== restarted SGC