Thank you for contacting us on that matter. Please note that I cannot be sure about your particular implementation. Hence, I am unable to reproduce and test the reported behaviour on our side.
However, you may find helpful our DragDropManager Migration article. Also, with the new drag drop logic we exposed the TreeViewDragDropOptions object. It exposes properties that control the visual feedback when you perform drag&drop operations in the RadTreeView control. You can find more information in our How To -> Drag and Drop section of our tree view documentation.
If these articles are not helpful in your particular case. I will need you to provide me with additional information about your implementation. I need to reproduce the issue on our side in order to investigate the reasons behind it and suggest an approach.
Thank you for understanding.
Pavel R. Pavlov
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