Well that would certainly explain things <blush>. The joys of an inherited WP site. Sorry to trouble you. I’ll go bug another plugin creator with this instead.
You can see the behavior here:
https://wabicc.makeduconsult.com/en/resource-center/gallery/
The thumbnails are https. The actual images are http. This staging site does not enforce https for the actual images, so the user is not aware. When we move to production, https is enforced, so the thumbnails work, and the big images are broken.
