This still hasn’t helped me. Fortunately I only updated one site and have been able to login via ftp and delete the plugin to regain access through the default wp-admin address.
However, if I install iThemes Security again that all goes fine but when I enable it I get kicked straight back out again. There are no options in the dashboard to modify the settings so I’m screwed.
It doesn’t seem like it’s the Hide Backend setting that’s wrong here, it feels more like the ‘Away’ settings. I had mine set to block access in the early hours of the morning but it seems to be doing it 24/7 at the moment.
So now I have no security on one site and I’ll be leaving all my other sites on the old version for the time being.
FWIW perhaps the rebrand should have happened BEFORE the ground-up rewrite as you’ve now possibly catastrophically damaged your new brand.