When using the workbench core module, how can one assign a node to a new author and it show up in their list of content?
Workbench uses Views to render it's data. The trick - whilst new user is now considered author of a node, last edit was not his. So it will not be seen in "my edits".

Go to http://example.com/admin/structure/views/view/workbench_edited/edit.
You will see:



This filters by revision's author. Not what you want. What you need is to filter by node's user.  But this view does not have a relationship to content author:


Add missing relationship:


Filter is still using wrong relationship:


Make it use proper one:


Done. Repeat for other views as needed.