HTTP POST data not going from AJAX to C# MVC 5 Backend

As the title states, I'm trying to send data from a Javascript frontend to my C# MVC 5 backend, and it doesn't seem to make it. I've run through it with the debugger in Visual Studio and the data I'm trying to pass always ends up null.

Here is my front end code:

var file = $("#my-file").files[0];
file = file[0];
var formData = new FormData();
var MyData = {
    Name: "Form 133",
    Attachments: {
        Type: "Check"
    }
};
formData.append('file', file);
$.ajax({
    type: "POST",
    url: '/NMISProduct/Index',
    contentType: false,
    processData: false,
    data: { formData: formData, MyData: MyData },
    success: function (result) {
        console.log(result);
    },
    error: function (xhr, status, p3, p4) {
        var err = "Error " + " " + status + " " + p3 + " " + p4;
        if (xhr.responseText && xhr.responseText[0] == "{")
            err = JSON.parse(xhr.responseText).Message;
        console.log(err);
    }
});

Backend code:

[HttpPost]
public async Task<JsonResult> Index(MyData MyData)
{
    Debug.WriteLine(Request.Params["MyData"]);
    Debug.WriteLine(MyData.Name);
    try
    {
        foreach (string file in Request.Files)
        {
            var fileContent = Request.Files[file];
            if (fileContent != null && fileContent.ContentLength > 0)
            {
                // get a stream
                var stream = fileContent.InputStream;
                // and optionally write the file to disk
                var fileName = fileContent.FileName;
                var path = Path.Combine(Server.MapPath("~/App_Data/"), fileName);
                using (var fileStream = System.IO.File.Create(path))
                {
                    stream.CopyTo(fileStream);
                }
            }
        }
    }
    catch (Exception)
    {
        return Json("Upload failed");
    }
    return Json("File uploaded successfully");
}

public class MyData
{
    public string Name { get; set; }
    public Attachment Attachments { get; set; }
}

public class Attachment
{
    public string Type { get; set; }
}

As I stated, on the Backend MyData always ends up being null. What am I doing wrong?