CallGraphApiOnBehalfOfUser

[poundingCode]

I have built out the MS-Identity Advanced Scenarios successfully and deployed it to my sandbox in the Azure cloud and all is working as expected.
The customer application is in the GovCloud and I've run into problems (the code is identical, with the only change being the various Ids)
In my azure cloud version all of the user claims come back as expected.
In the GovCloud version HttpContext.User.Claims is empty

I am getting the following error which has lead me here.

No account or login hint was passed to the AcquireTokenSilent call.
IDW10502: An MsalUiRequiredException was thrown due to a challenge for the user. See https://aka.ms/ms-id-web/ca_incremental-consent.

The article: Managing incremental consent and conditional access has a line of code
dynamic me = await CallGraphApiOnBehalfOfUser(accessToken);

but I cannot find the underlying function call anywhere in this code base or anywhere else.

I think at issue is the fact that there may be some policy or other non-code related issue at play here as I've had two other engineers triple check that the registration and configuration of the App Registrations are correct.