In the previous version of the plugin thumbnail generations were broken when using this in combination with the new Jetpack Proton module. It is still not working on the latest updated version.
I don't need to use the Proton module on my development sites so this has not been an issue for me but some clients are asking about why proton is stopping the thumbnails generating. I done some looking online and found some issues to do with JQuery but did not look further into fixing it myself - and it seemed like the theory was off anyway since it coincided with activating the CDN for serving the images. I just disabled proton and things worked fine again for my clients but ideally them serving images from a CDN with minimal config needed would be a great boost for speed on some of their shared hosing packages.
Any help in fixing it on their sites would be appreciated or if a fix could be investigated within the plugin that would be even better lol