Usually when this happens, all blog post AMP elements for example using amp-img, amp-video etc will not display as AMP components is not provided by these readers.
Here's the result when integrating AMP HTML in-correctly on Blogger blogs, where you may have issues with your blog RSS and Atom feed -- Errors for Blogger Feed with AMP HMTL.
In addition, blog posts when shared using a Blogger blog RSS & Atom feed will create the same results, missing images, videos, media etc when viewed in blog aggregators, email body -- where AMP components/integrations is not available.
Blogger blog users who continues to use this, will need more work as they are missing one of the many powerful features to maximize a blog reach to wider (& targeted) audience -- very effectively -- via RSS & Atom feed aggregators.
Unlike Blogr-AMP and AMPaction Blogger theme, all blog posts are feed reader friendly, compatible to switch to any other Blogger themes while still becomes AMP valid on mobile devices.
You can check this Blog atom feed here or Blogr-AMP RSS feed here, which complies with any feed reader technologies.
Find out more on the fundamental of Blogr-AMP & AMPaction Blogger themes, how it utilizes existing Blogger built in functionality, compatible with any blog theme changes, complies to Adsense Policies & validates to AMP HTML specification at this Blogger AMP Resource page.
Or contact theme assistance for more information & resources -- we promise we do not bite!