Do some networks or browsers block binary file download from Cloudflare?

Hi all,

Has anyone seen instances of a corporate network or browser security policy blocking file downloads via Cloudflare that have a content-type: binary/octet-stream?

Context:

I recently updated our infrastructure to use Cloudflare. Cloudflare delivers images for https://www.cloudpano.com.

The infrastructure change was successful, but I am getting reports of one particular user in Arkansas, USA who can not view images delivered via Cloudflare.

The page at hand is: https://tour.shiningstarinteractive.com/tours/RLaFfGNLQOI

The user sees:

I and others from across the USA have no problem viewing this page. In fact, I have served over 4M requests and have not heard from any other users of problems across the globe.

So I am trying to figure out what may be causing this issue for the user. She claims she has tried from multiple devices. If true, it must be network related - all devices are on same network. I observe her screenshot indicates a VPN - maybe there is some security policy blocking the image?

The idea of a corporate network security policy being the culprit is further strengthened by this fact: The images are encoded as content-type: binary/octet-stream and downloading one results in a “may be a dangerous file” warning from Chrome. Perhaps networks and browsers don’t like this setup.

I just set up a worker to rewrite the content-type as image/jpeg, but I am waiting to hear back from the user - the chrome download warning is resolved now.

The user is non-technical and remote so it is difficult to do investigation - was hoping someone may have an idea of what is causing the problem for this particular user and if someone has seen something like this before.

Other details: We have end-to-end encryption: full (strict) set up and we auto upgrade http requests to https. I observed logs for this route and I saw a small number of 499 and 500 errors.

Bumping this as it was posted 3d ago but spam filter just release it today.