Latest Unity IAP throws an Exception when invoking RestorePurchases on UWP?

I've already reported this via a support ticket here, but due to the urgent nature (and for anyone else's benefit if they are googling this) I'm crossposting it here.

We are attempting to emergency update our product in the Microsoft Store, as the Unity IAP oddly stopped working out of nowhere. (Debugging a live version has been very difficult so we have no real idea yet, but based on our custom errors the store seems to possibly fail to initialize properly).

Anyways, figured the best place to start would be to update to latest Unity IAP (both packages). So we are at 2.2.7 in the Plugin side, and 2.2.2 on the Package Manager side. In Unity 2018.4.26f1.

While testing out the newest Unity IAP, we've run into an Exception that now gets thrown, when attempting to invoke via IExtensionProvider.GetExtension<IMicrosoftExtensions>().RestoreTransactions().

Regular IAP purchasing with the mockbillingsytem set to enabled appears to work as expected (it brings up the debug IAP menu we're used to), and the purchasing system is properly initialized when we hit this Exception, so we're beginning to suspect this might be a UnityIAP bug.

We'll continue to investigate while we wait to hear back from Unity, but in the meantime I wanted to get some input possibly on this b/c we are trying to fix this ASAP, as users are not able to purchase anything in our live app at the moment.

Error output from the Visual Studio console follows:

 

@skullthug We received your support request and looking into it. If we can find the issue, any fix would go into a future release. This should not affect initialization though, and is likely a separate issue. As mentioned in the support ticket, remove the restore logic as a test to confirm.

 

Also at 2.2.7 on the Plugin side, and 2.2.2 on the Package Manager side. In Unity 2020.2.6f1.
In app purchases fail to initialize after invoking

Code (CSharp):

1. UnityPurchasing.Initialize

with error:

Code (CSharp):

1. UnityIAPWin8:pollForProducts() Exception (persistent = False, delay = 0, retry = 30), exception: Exception of type 'System.Exception'

Steps to reproduce: follow the 4 year old documentation at https://docs.unity3d.com/Manual/UnityIAPWindowsConfiguration.html

 

Separate (but valid) issue. This thread is discussing RestoreTransactions callback when using the mockBilling flag during testing (which is a low priority issue and not likely to be addressed soon)