Are you able to see the Chromecast Audio from the Google Chrome browser running on the same PC as your Roon Core? To check this, click the “three dots” menu on the right side of the Chrome window, and click the “Cast” menu option.
If the Chromecast Audio does not appear in this menu, it is likely you have a network configuration error that is preventing multicast packets from being exchanged between your computer and the rest of your network. I would start by disabling any firewall or antivirus software you may have enabled on your PC and then checking the Chrome Cast tab again.
Ahhh… It was the Windows firewall. Roon was not allowed to go through it. Weird since at one point Roon found Chromecast and at next it did not. And I never made any changes to the firewall… Anyway now Roon finds it. So thank you very much!