After the most recent update, I first of all had to go to the settings and allow editors to be able to copy posts.
And then when copying a post (as a new draft for example), the page just sits there with the browser loading indicator spinning. After waiting and nothing happening, I refreshed the page, and could see a draft had been added because the links above the posts said "Drafts (1)", but when clicking to view them, the table was empty.
A client also said they were getting errors after trying to copy a post, and when they refreshed, 5 copies had been created. And then when trying to delete them, an error page showed again.