There are two common causes for this:

  1.  The thumbnail directory has changed since you set it in Settings or is not writeable
  2.  EasyIndex is running out of server memory while trying to create thumbnails

The thumbnail directory has changed or is not writeable

This may occur if you move servers or change your domain name which can invalidate your original directory setting.  If the thumbnail directory isn't found or isn't writeable, you'll see a page that has a header and sidebars (if your theme has those) but there will be no index content.  To fix an incorrect directory setting, go to the EasyIndex Settings page, clear the "Thumbnail directory" field, and save the settings.  EasyIndex should re-discover the correct directory.  If the thumbnail directory is not writeable, you should change the directory permissions so that it's writeable by the server process.

EasyIndex runs out of server memory

If PHP runs out of memory while EasyIndex is creating thumbnails, the process crashes silently and you can end up with a completely blank index page.  If this happens, try increasing the "Thumbnail memory" option on the EasyIndex Settings page to 384, 512 or higher. You might also use the "Generate Thumbnails" option on the index edit page which will show you the progress and alert you if there are errors.