Figured out (I think) the issue with my Feedly feeds and images. I use BeautifulSoup and Django templates to rewrite the image tags generated by Trix to be lazy loading and offer optimized formats on the backend.
picture = BeautifulSoup( render_to_string("trix/picture.html", context),"html5lib" )
The issue is that the the "html5lib" causes my <figure> tag to be wrapped in <html> and <body> tags. Browsers are smart enough to filter this out. But these other parsers are not.
Changing this line to use the "html.parser" prevents wrapping my template in html tags and should solve the issue.
picture = BeautifulSoup( render_to_string("trix/picture.html", context), 'html.parser' )