Is it possible you've accidentally enabled a guest or automatic login (see link above)?
Have you contacted email@example.com as well?
Thanks for the link Matthew, it's strange. I checked and "Enable Guest" is clicked on. If I deselect it, the login pages come back for everything, including dashboards which we don't have user groups (which causes some issues). If I unselect it, the one site that hasn't been updated still asks for a login...but anything updated recently does not...
I'll shoot a message over to support as well.