I tried to reproduce this by adding the Diagram.contextMenu from the Basic sample to the Draggable Link sample. But I cannot reproduce the problem, no matter how I select first (whether just the node or both the node and the link) and then how I copy (whether copy-and-context-menu-paste or copy-and-paste or control-copy-drag-and-drop).
Furthermore I was unable to reproduce the problem on a tablet without even adding the Basic sample’s Diagram.contextMenu, since on tablets there’s a default context menu. Again, it worked well there.
So can you help us reproduce the problem?
By the way, today’s officially a holidy, so it may be a while before someone responds.