customadmin/admin-ajax.php accessible but scan doesn’t start

Hi for security reasons I “hide” wp-admin (using htacess) and I have a custom /wp-admin/ = /customadmin/

The url http://mydomain.com/customadmin/admin-ajax.php?action=wordfence_testAjax returns WFSCANTESTOK but the Wordfence scan doesn’t initiate.

Any ideas?