[Unity] IAP.GetViewerPurchases() returns Platform error

Hello, I am facing a weird issue with my IAP in my testing account where every time, I try to fetch user purchases:

IAP.GetViewerPurchases().OnComplete(msg =>
{
    if (msg.IsError)
    {
        Debug.Log($"Error: {msg.GetError().Message}"); //lands here every time
        return;
    }
//other code
}

and this is error message:

OVRPlatform [Purchase] Purchase::deserialize: response object field "grant_time" was not a uint64. Value is: -120

and my log message:

Error: Server response is not valid JSON.

This started happening after my test subscription expired and I deleted the subscription from my dashboard.

-- UPDATE --
Same issue with `IAP.GetViewerPurchasesDurableCache()`

-- UPDATE 2 --
Looks like this problem is occurring with `IAP.LaunchCheckoutFlow` as well. In my opinion, this is likely a test account only issue but there is no way to confirm.