Store API (purchase.mp.microsoft.com/v8.0/b2b/recurrences/query) always returns empty list

Question

I would like to get the user ownership through API

purchase.mp.microsoft.com/v8.0/b2b/recurrences/query (https://learn.microsoft.com/en-us/gaming/gdk/_content/gc/commerce/service-to-service/microsoft-store-apis/xstore-v8-recurrence-query).

I've followed the instruction here:

https://learn.microsoft.com/en-us/windows/uwp/monetize/view-and-grant-products-from-a-service

Here is what I did briefly, step by step:

1. Created new app (https://apps.microsoft.com/detail/9ppkxvwx9n6n?hl=en-US&gl=US) and registered in Azure Active Directory.
2. Associated app registration's identifier with our app through Partner Dashboard.

Created three Azure Active Directory (AAD) tokens for following audience URIs:

• https://onestore.microsoft.com (used in step 5 for authorization)
  • https://onestore.microsoft.com/b2b/keys/create/collections (used in step 4)
    • https://onestore.microsoft.com/b2b/keys/create/purchase (used in step 4)
    Created Microsoft Store ID keys for Collection and Purchase APIs on behalf of our test Microsoft account by calling StoreContext.GetCustomerCollectionsIdAsync and StoreContext.GetCustomerPurchaseIdAsync respectively from client code in our app. To generate each key we used corresponding AAD token from step 3.

1. Requested ownership for the user by calling
   https://purchase.mp.microsoft.com/v8.0/b2b/recurrences/query, with AAD token from step 3 and request body
   { "b2bKey":"the purchase ID key got at step 4", "sbx": "XDKS.1" }

So we're getting 200 "OK" response, but the list is always empty.

The app at MS store is not free and we made a purchase for one user. Could you help me to look into it? It actually a major blocking issue right now for us. Thanks.

BR,

Hao