Images inconsistently loading

Safari local: all images load
Safari S3: random images don’t load
Chrome S3: all images load

https://noredink-product.s3-us-west-2.amazonaws.com/design-prototypes/al-3-5/2021dec/NoRedInk%20Web%20Viewer/index.html

I tried it on my Mac with Safari and could not reproduce it. Although it takes a whooping 19s to load the prototype with cache disabled (for 9.3 MB).

Couldn’t reproduce either, all images load.