right-click copy to library option missing

In the past I have been able to right-click on a book and there is an option to "Copy to another library", with an option whether to copy then delete from the current library. I have separate libraries for fiction, historical fiction, nonfiction, science fiction, fantasy, mystery, suspense, etc., etc. I often want to move books from one library to another. However, I no longer have that right-click option. Was it removed, or is there somewhere I can get it back in the settings? I am running 64-bit Calibre version 3.12 on Windows 10.
Thanks!