The essence of the problem. Adding the page to my bookmarks. Then, when I move the page to the left side of the binder, this page disappears from the bookmarks, but it does not change its location on the left side of the binder. This function used to work. I used it to sort the pages. I added the pages that I wanted to place in the right order to my favorites. And from there I moved them to the right place of the book on the left side of the binder.
Thanks for the report! This is a known problem that has been around for a long time. The only kinds of dragging and dropping currently supported are into a text editor (to make a link), and into the editor header bar to load it.
You mentioned it used to work—maybe it did, but it looks like this was never marked down as having been worked on, so I’ll add that note to the ticket.