The most recent update Version: 4.1.2 has raised some new issues with password protected pages/post which did not exist in Version: 4.1.1.
Now when passwords are entered into post/page on mapped domains the user is redirected to the https version of the domain to authenticate the password.
For reference you can see my previous issues which were solved here in previous versions https://premium.wpmudev.org/forums/topic/domain-mapping-not-working-with-password-protected-pages-or-post
This plugin is becoming very bloated with unnecessary features please just keep it simple. KISS