I'm testing the new Subscription Offers feature in iOS 12.2:https://developer.apple.com/app-store/subscriptions/#subscription-offersI have set up a Subscription Offer in App Store Connect, and the SKProduct property `discounts` contains this offer.I am generating a signature from the server according to:https://developer.apple.com/documentation/storekit/in-app_purchase/generating_a_signature_for_subscription_offersI have a test account which has purchased the original SKProduct, in order to be eligible for the offer.I'm also setting up a SKPayment with a SKPaymentDiscount correctly initialised with the signature return values.However, when attempting to purchase the offer the transaction fails with the following error:Error Domain=SKErrorDomain Code=12 "Cannot connect to iTunes Store" UserInfo={NSLocalizedDescription=Cannot connect to iTunes Store}Also, in the Console I can see an error for the process `itunesstored`:StoreKitClient: Buy failed with error: Error Domain=SSServerErrorDomain Code=3903 "Cannot connect to iTunes Store" UserInfo={NSLocalizedDescription=Cannot connect to iTunes Store} for payment: (entity: MicroPayment; id: 0xab06487fa50b06c0 ; data: )Does anyone know if this indicates an issue with the paramters on the client side, or is there an issue with this feature within StoreKit as this is in beta?