M365 Private CDN redirect - incomplete query params

We are having an issue with a client of ours where profile pictures are not loading (everything else works fine). They're on the private M365 CDN, we can confirmed the permissions are correct and the web request has the required headers to be able to access the content.

The first web request to get the profile picture has the correct query params, and the response from the server also includes all the correct information.

The second web request to retrieve the profile picture itself from the given location has the correct params listed, but the accountName query string doesn't include the name of the person, despite it being listed in the response from the server. The accountName query string is only i:0, should be i:0|membership|$emailaddress

Manually fixing the request using Postman results in the profile picture correctly loading.

They were running an older version of the web app but I have updated them to the latest with no luck yet.

Any assistance would be appreciated, I can provide screenshots if required.