$_REQUEST works, but $_POST doesn’t –

Thank you for sharing in my headache – here is the short speil:

Recently inherited a poorly coded WordPress site – which leveraged a WP Contact Form 7 –

I stripped all the WP-CF code out (due to the fact that the WordPress had been stripped out before it was handed over to me) — just to make a simple patch script and get on with real work.

I replaced the WPCF scripts with this one: (to make things as easy as possible for me):

jQuery(document).ready(function() {
 $ = jQuery;
 console.log("Ready");
 $("#quack-button").click(function(e) {
   console.log("Quack"); 
   e.preventDefault();
   e.stopPropagation();
   POSTDATA = $.param($("#quack-form").serializeArray());
   $.ajax({
     method : "POST",
     url : "http://www.domain.com/contact.php",
     data : POSTDATA,
     success : function(response) {
      console.log(response);
      alert("Thank you ! We'll get in touch as soon as we can -! ");
     }
   });
 });
});

but, after trying many different forms/combinations of $.param and serialize –
The server side script continued to return a blank array….

print_r($_POST);

However, when I changed it to print_r($_REQUEST) – it all worked, fine….

Now, what possible ways could this even happen? What blindspots am I missing that could create this sort of scenario…?

This is the most baffling I’ve dealt with in some time… I appreciate any understanding anyone can throw at this…