Get subscriptions for a user api fail

Question

Hello,

We're seeing that some of our get user subscription api calls are failing with 'Unauthorized' error. Here is the documentation that we're referencing to make the api call: https://learn.microsoft.com/en-us/windows/uwp/monetize/get-subscriptions-for-a-user

Note that this does work for some users but fails for others. I've attached the api response for reference and not included any api keys/client ids.

-Thanks

{
"code": "Unauthorized",
"data": [],
"details": [],
"innererror": {
"code": "AuthenticationFailure",
"data": [
"Processing of the HTTP request resulted in an error. StatusCode: Unauthorized, PurchaseFD : Unauthorized : The client is not authorized to perform the requested operation. : { : AuthenticationTokenInvalid : Authentication token supplied is invalid : [B2B key]}"
],
"details": [],
"message": "The Authorization header is invalid",
"source": "PurchaseFD"
},
"message": "The client is not authorized to perform the requested operation.",
"source": "PurchaseFD"
}