Change 1000+ of WordPress Featured Images in 5 Minutes! › Forums › Questions and Answers › Future Featured Image › Reply To: Future Featured Image
It seems that the origin CMS was WP, too. Because in the posts content the images have attritute values like
1234 as the ID of the image in the WP database. But there are no entries with the IDs found in the contents.
The contents are well prepared to let the plugin work finely. If it would be possible for you to import the missing image data into the database you would not only see all images in the media library. The lightbox popup would work (now it is broken) and the plugin would set the first content images as featured.