Good evening Colin and welcome back!
Thank you for reaching out to us.
I would love to help you with this topic.
It looks like your specific WordPress theme is trying to force the medium sized thumbnails.
There are a couple of things to do to fix that:
- Cheat by changing the medium size in WP admin media settings (i.e.: 720px) and regenerating the thumbnails. This will do the trick, but it will also impact any other medium sized image on your website.
- Force the full-size image as part of a template override (custom view). You might want to read our Themer’s guide to get a sense of how that works.
Could you please send me a copy of the latest version of your WordPress theme / child theme via a link to a .zip file link (stored Dropbox or Google Drive) so that I can run some tests on my end ? I recommend a private reply for that purpose.
Please ensure you are using the latest files as found on your actual website.
This way I will get access to any updates or customizations you might have made.
Let me know if that helps.
Have a great day!
Geoff B.