Thanks for the quick reply! I’ve depersonalized, but this is an example:
<img width="640" height="360" src="http://our-domain.com/wp-content/uploads/2016/02/filename-1320x743.jpg" data-src="http://our-cdn.com/wp-content/uploads/2016/02/filename-640x360.jpg" class="attachment-thumbnail size-thumbnail wp-post-image lazy-loaded" alt="Our alt text." data-srcset="http://our-domain.com/wp-content/uploads/2016/02/filename-640x360.jpg 640w, http://our-domain.com/wp-content/uploads/2016/02/filename-1320x743.jpg 1320w, http://our-domain.com/wp-content/uploads/2016/02/filename-1600x900.jpg 1600w" sizes="(max-width: 640px) 100vw, 640px">
We were testing yesterday with the CDN turned off, so I’m pretty sure that’s not the issue?
The data-srcset is uncustomized, as added by WP.
