Hello,
I would like to report a fix to be made for the compatibility with WPML. Some years ago the compatibility fix below was inserted into the file /wp-content/plugin/all-in-one-wp-security-and-firewall/classes/wp-security-process-renamed-login-page.php, lines 185-191.

/*
 * Compatibility fix for WPML plugin
 */
if (function_exists('icl_object_id') && strpos($home_url_with_slug,$login_slug)){
    $home_url_with_slug = home_url($login_slug);
    function qtranxf_init_language() {}
}

Well now it causes issues, pephaps because it was deprecated and removed from version 3.3, as you can see here: https://wpml.org/documentation/support/creating-multilingual-wordpress-themes/language-dependent-ids/

In particular, it sends 404 error if the login url has been edited in the brute force section.
To solve this issue, the code has to be removed, as you could see in the solution posted in this WPML forum page: https://wpml.org/it/forums/topic/incompatibilita-con-all-in-one-wp-security-firewall-errore-404/
I hope it helps and I hope that fix will be implemented soon in a future update.
Regards