The only thing that comes to my mind right now is that you accidentally applied your override rules to admin siteaccess.
Admin interface doesn't need any overrides or special templates for each class. It always uses it's own templates do display every class out there.
So, make sure that the overrides you added to override.ini are NOT being applied to admin site access. For example, if you keep your overrides in settings/override/override.ini.append.php, move them to settings/my_frontend_siteaccess/override.ini.append.php
