I am unable to reply to the original thread about the cert error but I see an error as well when visiting https://hubzilla.org:

hubzilla.org uses an invalid security certificate.

The certificate is only valid for demo.hubzilla.org


!Hubzilla Support Forum
I tried "refresh permissions" which didn't change anything.
@Brian Christensen
Please re-check, added cert and redirect for https.
Works perfectly now.