[Domain Mapping] Login mapping - "domain entered by the user" doesn't work

I've patched this on my own site already. But the issue is that you have this code:

if (self::utils()->is_login()) {
    $use_mapped = ($this->_plugin->get_option( 'map_logindomain' ) === 'original' ? false : true);
}

You're setting $use_mapped to true unless the option is "original". But I have it set to "user", which isn't covered in your if statement.