Closing the loop. I was contacted by Innuos Support with the message that it seems that some of the recent/latest Roon updates may be triggering some issues for some customers.
This may be a case of a corrupted Roon database. To resolve, I needed to clear the current Roon database by going to innuOS dashboard > SERVER > SETTINGS > INTEGRATIONS > Roon > TROUBLESHOOTING > CLEAR ROON DATABASE.
This does not delete any of the Album folder/files stored on the server. Was then able to find and connect to the ZEN’s Roon Core server.
I did need to reconfigure Roon and restore it from a recent existing Roon backup, but I am back up and running and didn’t lose a thing.