Hi, I am glad you found what was causing the issue. In regards to your comment.
But does it mean my site is less protected as this option is a basic one ?
To some degree you could start getting attempts at login into your website but if you have either option from the Brute Force enabled i.e. Rename Login or Cookie Based Brute Force Prevention will stop any attempts.
This is explanation the developers provide about the feature you disabled.
This setting will add a directive in your .htaccess to disable access to the WordPress xmlrpc.php file which is responsible for the XML-RPC functionality such as pingbacks in WordPress.
Hackers can exploit various pingback vulnerabilities in the WordPress XML-RPC API in a number of ways such as:
1) Denial of Service (DoS) attacks
2) Hacking internal routers.
3) Scanning ports in internal networks to get info from various hosts.
Apart from the security protection benefit, this feature may also help reduce load on your server, particularly if your site currently has a lot of unwanted traffic hitting the XML-RPC API on your installation.
NOTE: You should only enable this feature if you are not currently using the XML-RPC functionality on your WordPress installation.
Ultimately you could share this information with the IFTTT developers.
If your issue is resolved can you mark this support thread as resolved.
Thank you