[UWP] Get subscriptions is empty for some users and a lot of subscriptions are stuck in dunning state for long time over their expiration time

Question

In the UWP app, there are subscriptions, users can purchase different types

Problem 1:

When we query the store purchase API (https://learn.microsoft.com/en-us/windows/uwp/monetize/get-subscriptions-for-a-user) to get a list of subscriptions for each user, some users would have an empty list like this

{ "items": [] }   

even if they send a screenshot from their Microsoft account shows that they have the subscription and they have paid for it, we can not see it through the store api, any idea why this could be happening?

Problem 2:

A lot of subscriptions are stuck in dunning state which according to the documentation https://learn.microsoft.com/en-us/windows/uwp/monetize/get-subscriptions-for-a-user#response

The subscription is in dunning (that is, the subscription is nearing expiration, and Microsoft is trying to acquire funds to automatically renew the subscription).

They're in this state even after expirationTimeWithGrace has been reached and is in the past, which doesn't make sense according the expirationTimeWithGrace description in the documentation

The date and time the subscription will expire including the grace period, in ISO 8601 format. This value indicates when the user will lose access to the subscription after the subscription has failed to automatically renew.

also a lot of subscriptions are back to state Active after being InDunning state for long time over expirationTimeWithGrace, so should we ignore the expiration date at all as long as subscription state is in dunning? any explanation for this behavior?