Yes, we clicked save. I just refreshed and now it says in the custom domain window that the CNAME cannot resolve to ArcGIS Hub. Didn't say that before.
EDIT: We had a different CNAME in there to test. It's correct CNAME (hub.arcgis.com) again. Site still doesn't connect though.
Any luck on this? We just added a CNAME to the DNS for our hub site, and I got the message that everything had worked and that it had to redirect me to the new page to continue edits. The new page says that the site was able to validate the CNAME. But the new page says it cannot be displayed. It propagated through AGOL, because the "View Application" option in my Content page now takes me to the CNAME, but again, it is not displaying.
I'm getting errors about the Certificate on every web browser I try it on, that the certificate has issues. I've tried it both with and without HTTPS enforced.
Firefox: Warning: Potential Security Risk Ahead / Connection Not Secure
New Site: https://gisportal.franklincountypa.gov/