Originally Posted by kovidgoyal
look in a subdirectory, calibre *always* generates OPF and NCX files when creating EPUB
I realize this is an old thread, but I'm having the same problem. Which subdirectory? I've looked in every relevant one (there aren't that many) and don't see it. It's not in the zip file, the author folder, or the book-title subfolder. Kindle viewer and Kindle for PC do show a toc.ncx, but it's just not there as a separate file.