ProcessPurchase not called when Subscription is modified on iOS

We have not heard of this behavior. What IAP version? Do you mean a different subscription? You can only subscribe once per subscription, but you can have multiple (separate) subscriptions as long as they are defined as separate products. Please share your code, are you using a SubscriptionManager? Improved Support for Subscription Products Please provide a screenshot of the Apple popups that you see, and if you can reproduce, the device logs How To - Capturing Device Logs on iOS