If you want to see the DragCue when you start to drag by the header you'll have to cancel the default drag and drop in the RadTileView. You can do this by handling the PreviewTileDragStarted event like this:
sender, TileViewDragEventArgs e)
Note that in this case you won't have the default TileView DnD.
I've updated the attached project so you could examine it and if you have more questions please feel free to ask.
All the best,
the Telerik team
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