private void TreeViewAdv_Loaded(object sender, RoutedEventArgs e)
Expander expand = VisualUtils.FindDescendant(treeview, typeof(Expander)) as Expander;
if(expand != null)
expand.Visibility = Visibility.Collapsed;
Thank you for your update.
We have checked your query and we were able to reproduce the reported behavior on dragging the TreeViewItems. We are currently validating your reported behavior with TreeViewAdv in source level. We will check and update you the complete details on or before 16th Dec 2019.