1. Add the admin-ajax.php skip/bypass rule below to this wp-admin Custom Code text box: CUSTOM CODE WPADMIN PLUGIN/FILE SKIP RULES
2. Click the Save wp-admin Custom Code button.
3. Go to the Security Modes page and Activate wp-admin Folder BulletProof Mode.
Note: The skip rule must be [S=2] because it will be written to your wp-admin .htaccess file above skip / bypass rule [S=1]. If you have other wp-admin skip/bypass rules already then either combine them or add this skip/bypass rule separately above the other rules and change the skip #. Example: If you already have skip #’s 2 and 3 then this rule would be skip rule #4.
# admin-ajax.php skip/bypass rule
RewriteCond %{REQUEST_URI} (admin-ajax\.php) [NC]
RewriteRule . - [S=2]