Clarine, the Copy and Paste function normally works fine, however, if you copy and it seems to only add a “blank” layer, it is possibly because there is a selection that is copied. Sometimes, that selection is tiny and you don’t see it (it has happened to me too). In that case, you need to Deselect where you copy, to make sure any tiny selection is gone. You can do that by going to Selections > Select None or use the keyboard shortcut of Ctrl-D.
Another oddity of the copying function is that if the vector shape tool is active, it does not seem to copy to the clipboard, and when you paste, you get nothing at all. Just activate a different tool and it will work. This is an old “bug”.