Ajax post request correct, but failing on IIS - php

Question

Built a site out on an apache server and it has now been moved to its final home on an IIS server running php 7.2. I use jQuery based ajax post requests on the site for sending form data to the back end and updating the page. This worked great on the apache server, but once I get the code and database up on the new IIS server, this stopped working. The network tab in the developer console shows the file is being hit, and I get a status 200 back. The header shows the form fields correctly, but there is nothing in the response from the file (should just be an echo of the post array.
Here is the ajax request:
$.ajax({
type: 'get',
url: '/ajax/users.php',
data: 'createUser=1&' + $("form[name=addUser]").serialize(),
success: function(msg) {
console.log(msg);
}
});
And here is the /ajax/users.php file:
<?php
error_reporting(E_ALL);
ini_set('display_errors', 1);
echo "<pre>"; print_r($_REQUEST); echo "</pre>";
?>
Headers:
Request Method: POST
Status Code: 200 OK
RESPONSE:
Content-Length: 169
Content-Type: text/html; charset=UTF-8
Date: Thu, 27 Sep 2018 05:59:20 GMT
Server: Microsoft-IIS/8.5
X-Powered-By: PHP/7.2.7
REQUEST:
Accept: */*
Accept-Encoding: gzip, deflate
Accept-Language: en-US,en;q=0.9
Connection: keep-alive
Content-Length: 95
Content-Type: application/x-www-form-urlencoded; charset=UTF-8
Host: somehost
Origin: http://somehost
Referer: http://somehost/users
If I directly navigate to the file and put the form data in the URL, the page works as expected, it only has this issue when it is via an ajax request (get or post), and only on this IIS server. On the old Apache, the code works as expected.
Any ideas of a setting I might be missing? Or why AJAX would not work properly? I don't control the server personally, but have access to that person via email.