I am trying to import an Aperture library. It seems the importer cannot determine the number of files in my Aperture library and I cannot proceed with the import because the Import button is inactive as seen in the attached screenshot.
The built-in Aperture/iPhojne Importer Plugin is very buggy and unsupported by Adobe. You could try the third-party Avalanche program, which has a pretty good reputation (but costs money).