EJS Grid duplicate rows after insert

When executing add method on the grid the row is properly added to the system, new row shows up in the grid, but also one additional row is added - only in the view itself because the JSON data behind doesn't have this row.  Then changing the grid order duplicate this empty row. 
Scenario:
1. one funky grid 

2. lets add record 
3. dafuq is this?

4. oh no!

5. please stop!

6. Can't even delete it! 

Doesn't matter if  I  return an added object (grid displays it properly) or null, the additional empty row is always added. 

How to solve this? 

and check this not working url :)  https://ej2.syncfusion.com/aspnetmvc/documentation/grid/global-and-local

[index.cshtml]      @Html.EJS().Grid("Grid").ActionBegin("actionBegin").DataSource(dataManager =>{dataManager.Json(ViewBag.dataSource).InsertUrl("/Home/Insert").RemoveUrl("/Home/Delete").UpdateUrl("/Home/Update").Adaptor("RemoteSaveAdaptor");  }).EditSettings(edit =>  {      edit.AllowAdding(true).AllowEditing(true).AllowDeleting(true).ShowDeleteConfirmDialog(true)          .AllowEditOnDblClick(false).Mode(Syncfusion.EJ2.Grids.EditMode.Dialog);  }).Columns(col =>  {      col.Field("OrderID").HeaderText("Order ID").Visible(false).IsIdentity(true).IsPrimaryKey(true).Width("30%").Add();      col.Field("EmployeeID").HeaderText("Employee ID").Width("150").Add();      col.Field("CustomerID").HeaderText("CustomerID").Width("70").Add();    }).AllowPaging().Toolbar(new List<string>() { "Add", "Edit", "Delete", "Update", "Cancel" }).Render()    </div>    <script>      var PkValue = 1000;        function actionBegin(args) {               if (args.requestType == 'save' && args.action == 'add') {              args.data[this.getPrimaryKeyFieldNames()[0]] = ++PkValue;          }      }  </script>      [controller]    public ActionResult Index()          {              ViewBag.dataSource = OrdersDetails.GetAllRecords().ToArray();              return View();          }            public ActionResult Update(OrdersDetails value)          {              var ord = value;              OrdersDetails val = OrdersDetails.GetAllRecords().Where(or => or.OrderID == ord.OrderID).FirstOrDefault();              val.OrderID = ord.OrderID;              val.EmployeeID = ord.EmployeeID;              val.CustomerID = ord.CustomerID;              return Json(value);          }          //insert the record          public ActionResult Insert(OrdersDetails value)          {                OrdersDetails.GetAllRecords().Insert(0, value);              return Json(new { data = value });          }          //Delete the record          public ActionResult Delete(int key)          {              OrdersDetails.GetAllRecords().Remove(OrdersDetails.GetAllRecords().Where(or => or.OrderID == key).FirstOrDefault());              var data = OrdersDetails.GetAllRecords();              return Json(data);          }      . . .     }

• Please share the EJ2 version details

• Please share the full grid code example

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• Please share the sample if it is possible

I have reproduced the issue with your example project. 
Just change reference to:    src="https://cdn.syncfusion.com/ej2/dist/ej2.min.js"

I just checked the new 16.4.40-beta version and the issue is not fixed :(

It's now end of January 2019. Has this issue been resolved? Solution path appreciated