Description When starting Live Activities via ActivityKit push notifications, the “start” notification is received correctly on iPhone 16 Pro Max, but subsequent update or end push notifications are not. The same implementation on iPhone 16 Pro behaves as expected (both start and update/end notifications are delivered and processed). Environment Property Value Device (failing) iPhone 16 Pro Max Device (working) iPhone 16 Pro iOS Version 18.5 Xcode / SDK 16.2/ActivityKit / Push Notifications Network Wi-Fi / Cellular (both tested) Data Collection Method Devices connected via USB. Logs captured using Console.app. Log filtering applied for the liveactivitiesd daemon to isolate Live Activity behavior. Initial Triage/Observations Payload format confirmed compatible; no incompatible fields. APNs token remains the same across messages (no refresh). Identical ActivityKit subscriptions/participants on both devices. Server-side delivery is confirmed: iPhone 16 Pro receives all messages (start, update, end). Only iPhone 16 Pro Max fails to receive update or end push notifications. Log Analysis iPhone 16 Pro (Working) Push-to-Start successfully received: 13:45:20 - APSXPCDeliverMessageEvent: Created APSIncomingMessage 13:45:20 - Received message: eventType: start(SessionPushNotifications.IncomingMessage.EventType.StartParameters(attributesType: "AchToLSUpgradeAttributes", attributesData: 125 bytes, inputs: [])) 13:45:20 - Created activity: 1C081AC5-01AE-4EC0-8B67-5F2A9FAE2D60 13:45:45 - APSXPCDeliverMessageEvent: Created APSIncomingMessage 13:45:45 - Received message: eventType: end(dismissDate: Optional(2025-07-21 21:00:44 +0000)) 13:45:20 - Activity updated: 1C081AC5-01AE-4EC0-8B67-5F2A9FAE2D60 13:45:20 - Local activity did update: 1C081AC5-01AE-4EC0-8B67-5F2A9FAE2D60 iPhone 16 Pro Max (Failing) 13:56:39 - APSXPCDeliverMessageEvent: Created APSIncomingMessage 13:56:39 - Received message: eventType: start(SessionPushNotifications.IncomingMessage.EventType.StartParameters(attributesType: "AchToLSUpgradeAttributes", attributesData: 125 bytes, inputs: [])) 13:56:39 - Created activity: E6BBF691-0C7A-4791-98D2-6F1440D9932E **No subsequent APNs push-to-update or push-to-end messages received.** 13:56:39 - No destinations for event E6BBF691... of type start 13:56:40 - No destinations for event E6BBF691... of type update Questions for Apple Engineering Are there known issues with ActivityKit push notifications specifically on iPhone 16 Pro Max devices? What additional diagnostic logs (system, APNs, liveactivitiesd) would be most helpful to collect? Could device-specific power management, notification settings, or OS-level changes on Pro Max models affect Live Activity updates? Are there differences in how Live Activity push subscriptions or routing are handled on iPhone 16 Pro Max vs Pro that could lead to this issue?

Hi Apple team, I'm experiencing a persistent issue with writing to UserDefaults from a widget extension on iOS. Here's the situation: I've set up an App Group: group.test.blah The main app has the correct entitlement and can read/write from UserDefaults(suiteName:) using this group successfully. I can read the value written by the app from the widget (e.g., "testFromApp": "hiFromApp"). The widget extension has the same App Group enabled under Signing & Capabilities. The provisioning profile reflects the App Group and the build installs successfully on a real device. The suite name is correct and matches across both targets. I’ve confirmed via FileManager.default.containerURL(...) that the app group container resolves properly. When I try to write from the widget extension like this let sharedDefaults = UserDefaults(suiteName: "group.test.blah") sharedDefaults?.set("hiFromWidget", forKey: "testFromWidget") ...I get this error in the console: Couldn't write values for keys ( testFromWidget ) in CFPrefsPlistSource<0x1140d2880> (Domain: group.test.blah, User: kCFPreferencesCurrentUser, ByHost: No, Container: (null), Contents Need Refresh: No): setting preferences outside an application's container requires user-preference-write or file-write-data sandbox access Questions: What could still cause the widget extension to lack write access to the app group container, even though it reads just fine? Are there any internal sandboxing nuances or timing-related issues specific to Live Activity widgets that could explain this? Is this a known limitation or platform issue?