I'm not able to copy items from a revision into the main project. It appears like the copied items disappears from the clipboard when the window with the revision is closed.
Possible solutions:
1) Allow project revision window and main project window to be open at the same time.
2) Let items remain in the clipboard even after the window gets closed
The reason this needs to work for me is because I had 2,000 optional items get stripped out of a project that got approved and I need to copy them from the revision back into the project.