Why can't i see php call in Mozilla's Net tab?

     $('#registerForm').submit(
        function()
        {
            event.preventDefault();
            callAjaxSubmitMethod(this);
        }
    );  

    function callAjaxSubmitMethod(form)
   {
    $.ajax({
    type: "POST",
    url: "lib/registration_validate.php",
    data: $("#registerForm").serialize(),
    dataType: 'json',
    success: function(response)
            {
                console.log("cominggggg");
                alert("s"+response.status);
            },
    error:function(response)
            {
                alert("e"+response.status);
            },
    complete:function(response)
            {
                console.log("Completed.");
            }       

     });
  }

This is how i am sending data to my php page.

    <?php
     include 'configdb.php';
     session_start();
     global $connection;
     echo "oops";
     if(isset($_POST['submit']) && $_POST['email']!='' && $_POST['password']!='')
    {   
    $email= $_POST['email'];
    $sql1 = "SELECT * FROM Users WHERE emailID = '$email'";
    $result1 = mysqli_query($connection,$sql1) or die("Oops");
    $response = array();
    if (mysqli_num_rows($result1) > 0)
    {
    $response['status']='Email Already Exists';
    echo json_encode($response);
    exit;
   }
   }?>

I am just processing for duplicate email registration. If ia run this code in my chrome, i can see php in net tab. I can see completed in console and e200 in alert.

In my mozilla browser, i don't get any console strings, alerts. I din't get php page call in Net tab too.

I just cleared cache too. So it's not coming from cache too. I cleared localStorage due to out of memory error in my mozilla.

I don't even understand this behaviour. No idea to how to debug further.