mairag on "[Plugin: Easy Add Thumbnail] Does not add featured image for old posts"

I activated the plugin and I checked to see if the images are uploaded, which they are, however it is still not setting the featured images for my old posts. Any suggestions?

https://wordpress.org/plugins/easy-add-thumbnail/

I have the same problem.

All my images are in the media library and attached to each post, I'm using a Genesis child theme so I'm not sure what should I check to know if featured images are compatible with this plugin.

Also, I found a little confusing that there's not too much info about how the plugin works, just activating and that's it?