Why does the Kendo TreeView delete nodes after drag and drop?

Question

I have a Kendo TreeView bound to a DataSource that is connected to a CRUD API via its transport object.

I now want to re-order nodes in the tree using drag and drop and save these changes to the DB.

I do this by calling .sync() on the DataSource in the dragend event handler of the treeview.

var commandsTreeview = $("#commandgroups-treeview").kendoTreeView({
    dataSource: myDataSource,
    dragAndDrop: true,
    dragend: function(e) {
        // sync changes to the db
        myDataSource.sync();
}

});

However this will create two ajax calls:

1. PUT with all updates
2. DELETEon the node that has been dragged and dropped.

In the API I could react on all changes in the PUT request and re-organize my object relations in tha database but then the object gets deleted afterwards.

This is really bad as in the database there is a bunch of other tables that have foreign keys on that object and get deleted on cascade, as well.

This is confusing me.

1. Why would a dragged object be deleted?
2. How can I prevent this from happening?

---

Edit: here's my workaround

1. Gather the information I need for my service
2. Calling my service manually
3. Remember what nodes are expanded
4. Cancel the changes that kendo stored in the datasource
5. Re-read the data from the service (the data has been manupulated by the drag and drop service call earlier, so it reflects the new order already)
6. Re-expand all remembered nodes, as the read call will close all tree nodes

Some code

//…         
dragend: function(e) {

    var dragAndDropData = {};
    dragAndDropData.dropPosition = e.dropPosition;
    dragAndDropData.sourceNode = JSON.parse(kendo.stringify(myDataSource.getByUid($(e.sourceNode).attr('data-uid'))));
    dragAndDropData.destinationNode = JSON.parse(kendo.stringify(myDataSource.getByUid($(e.destinationNode).attr('data-uid'))));

    $.ajax({
        url: myServiceUrl,
        type: 'get',
        dataType: 'html',
        contentType: "application/json",
        data: dragAndDropData
    })
    .done(function(data) {
        // remember expanded nodes
        var expandedItemsIds = [];
        commandsTreeview.element.find(".k-item").each(function (index, value) {
            var item = commandsTreeview.dataItem(this);
            if (item.expanded) {
                expandedItemsIds.push( item.id );
            }
        });

        // cancel everything the kendo widget has done wrong
        // e.g. wrong indexes or items marked to delete
        myDataSource.cancelChanges();

        // re-read the (correct) data from the server
        var promise = myDataSource.read();

        // reset expanded nodes
        promise.done(function() {
            $(expandedItemsIds).each(function(index, value) {
                var nodeToExpand = commandsTreeview.findByUid(myDataSource.get(value).uid);
                commandsTreeview.expand(nodeToExpand);
            });
        });

    })

}