amp for wordpress plugin is not handling amp-img

None of the uploaded images are being converted from img into amp-img making amp pages not rendering at all.
Whenever I add /amp/ to the end of a url, the page goes back to the non-amp page. I know it’s the images that are causing this issue because it is the only element that is returned with non-amp tag (img) and as soon as I remove the image, amp is rendered. Funny thing is that whenever I re-upload images, the img tags are converted into amp-img. AND of my three themes, the plugin is working on two of them, but not on the third.

I get no console errors.

HELP!