The Create and open a copy button from the Selections folder of the Content Manager can take a long time to work after clicking to the point of seem dysfunctional. If the length of time is setting you back significantly then you'll need to either create a copy of your work in the Compose tool by taking the steps in our Compose: The File Menu article to open your file and save a new copy or temporarily remove the composition from its Selections folder.

You can follow this article for future updates as the team works on resolving this issue.