I'm using google cloud storage with imgix through the media cloud plugin. After upgrading to 3.0, the "Keep WordPress Thumbnails" option no longer works. I have a github issue open and am happy to put in a PR for the fix if you let me know which method is best: https://github.com/Interfacelab/ilab-media-tools/issues/89
Thanks for your work on Media Cloud! It's a pretty amazing plugin.