When uploading a new jpeg, or trying to regenerate thumbnails for jpegs, additional media sizes are NOT CREATED (e.g. 'thumbnail', 'medium', 'large', any other custom sizes), due to some issue with this plugin.
This is not a problem with other image file types such as .pngs or .gifs. Yes I know that just uploading a png instead of a jpeg will avoid this issue, however sometimes that's not an option, thus contributes to optimization issues site-wide.
Please consider fixing. This is a great plugin, one we would love to continue using, but cannot until issue has been fixed.