I have tried this plugin with the following setup
WP: 3.6.1 & 3.7
With this theme: http://themeforest.net/item/powermag-the-most-muscular-magazinereviews-theme/4740939
I have reached out to the author and he was not sure exactly why the plugin would not work... as he suggested using it to help me resize my featured images.
I syndicate articles and have a plugin I use to grab and apply a featured image - that plugin is:
Could it be the way this plugin applies the image that would prevent this regenerate plugin to affect the images properly? I am not sure what else to do. My images are not conforming to the size the theme has setup. Any thoughts would be helpful. Thanks.