not serving scaled images with plugin activated

Hello,
I′m using this Plugin quiet some time and was very happy with this.
Recently I found out, that the Plugin is causing some issues with the WP Multisite installation and other Plugins.
I′m using Envira Gallery and on the portfolio website it′s loading scaled images.
With the domain mapping plugin installed, it′s not loading the scalled images, it′s loading the original size images instead, what′s huge file size and is slowing down the site.
Any idea how to fix this?
Would love to use the plugin in the future still.
Thanks a lot