Microsoft Store Web API Query For Products Always Returns Empty List

Question

I have an app in the store.

The app has a Developer-Managed Consumable Add-on.

I'm attempting to consume the add-on from an ASP.Net Core / Azure App Service.

I have successfully configured the keys required and associated the Azure AD Client ID in Microsoft Partner Center.

I have successfully created Azure AD access tokens, one for the Bearer header with https://onestore.microsoft.com audience, and the second for https://onestore.microsoft.com/b2b/keys/create/collections, which is sent to the client, which successfully calls GetCustomerCollectionsIdAsync on the store context. This returns the resulting Store ID to the service, which attempts to list products for the user.

That request succeeds (200), but the returned list is always empty. I've tried all the different types, and none of them returns anything. My application can call GetConsumableBalanceRemainingAsync, which returns a BalanceRemaining of 1, as expected.

I'm quite baffled at this point. I've tried quite a few things to get this to work, various filters - specifying the Store ID / Sku ID, etc. etc. Nothing seems to work.

Am I missing something with the add-on type? The terminology in Partner center calls my add-on a Consumable (Developer-Managed), while the service API has type "UnmanagedConsumable". In any case, I can't even query for the application itself.

Thanks