unable to send array data using ajax with asp.net core

Question

I am trying to send array to the controller but it's blank in the controller parameter.

 

ajax function is

$('#pending').click(function () {
            SaveTestResult("/Reception/PatientTests/SavePendingTest");
        });
        function SaveTestResult(url) {
            var pid = $('.patientId').attr('id');
            var tid = "";
            var tval = "";
            var tpid = "";
            var tests = [];
            $("table > tbody > tr").each(function () {

                testId = $(this).find('.tid').val();

                if (typeof (testId) != "undefined") {
                    tid = testId;
                }

                var rowText = ""

                $(this).find('td').each(function () {

                    tpid = $(this).find('.tpId').val();
                    tval = $(this).find('.result').val();
                    if (typeof (tpid) != "undefined") {
                        tests.push({ PatientId: pid, TestId: tid, TestParameterId: tpid, TestValue: tval });
                    }
                });

            });
            //alert(JSON.stringify(tests));
            $.ajax({
                type: "POST",
                url: url,
                data: JSON.stringify(tests),
                contentType: "application/json",
                headers: { "RequestVerificationToken": $('input[name="__RequestVerificationToken"]').val() },
                success: function (data) {

                    alert(data);
                },
                error: function (e) {
                    alert('Error' + JSON.stringify(e));
                }
            });
        }

this is the controller

[HttpPost]
[Route("Reception/PatientTests/SavePendingTest")]
public async Task<IActionResult> SavePendingTest(List<PendingTestResult> pendingTestResult)
{
    if (ModelState.IsValid)
    {
        foreach (PendingTestResult ptr in pendingTestResult)
        {
            _db.Add(ptr);
            await _db.SaveChangesAsync();
        }

       // return new JsonResult("Index");
    }

    return new JsonResult(pendingTestResult); ;
}

But when run the code I see data array filled but inside of the SavePendingTest action, pendingTestResult is empty and not filled! I also try [FromBody] tag inside action params but it does not work too! help me to resolve this