This issue has been ongoing for a long time. It seems to either fail completely, only import media or only import posts depending on the export. As the images are not attached to the correct posts, it causes the WordPress SEO plugin to be unable to redirect visitors to the attached page as there is no attached page. The images inserted into the posts and pages are directly linked from the source and the media is not correctly imported and attached as it should be. I fail to understand why WordPress would state that it works with 3.6 when almost all of the support tickets are stating that media import is failing. Surely a bug report has been opened? Could WP be wary of removing the plugin as it forms part of WordPress and removal would cause a lot of issues.