I'm reporting a critical Health data synchronization failure that began immediately after updating from watchOS 18 to watchOS 26.0.2 (stable release) and persists in watchOS 26.1 beta 2. Bug Description: Complete failure of Health data sync from Apple Watch to iPhone Health app. All health metrics are being captured and stored locally on the watch but fail to sync to the paired iPhone. Affected Data Types: Activity rings (Move, Exercise, Stand) Heart rate measurements Sleep tracking data Workout data All other HealthKit data points Environment: Device: Apple Watch Series 7 Initial failure: watchOS 26.0.2 (23R362) - stable release Current: watchOS 26.1 beta 2 (23S5052c) Paired iPhone: iPhone 17 Pro Max, iOS 26.1 beta 2 (23B5052c) Bluetooth and Wi-Fi connectivity: Normal Watch pairing status: Connected and functional for all other features Reproduction: Updated Apple Watch Series 7 from watchOS 18 to watchOS 26.0.2 on September 30, 2025 Health data sync ceased completely starting October 1, 2025 Issue persists after updating to watchOS 26.1 beta 2 and iOS 26.1 beta 2 Data remains stored locally on watch and is viewable in watch apps Apple Watch appears as connected data source in Health app but no data transfers Troubleshooting Performed: Multiple device restarts (both iPhone and Apple Watch) Bluetooth/Wi-Fi toggling and reconnection Verified Privacy > Motion & Fitness > Fitness Tracking and Health enabled on both devices Confirmed data source priority settings in Health app Extended charging periods to allow background sync operations Verified no Low Power Mode restrictions Impact: Critical functionality loss for primary Apple Watch use case. Unable to track longitudinal health data, breaking continuity of health records dating back to watchOS 18. Feedback Submitted: FB20533870 filed via Feedback Assistant with sysdiagnose from both devices Questions for Engineering: Is this a known regression in watchOS 26.0.2 or later builds? Are there any watchOS 26.1 beta release notes addressing HealthKit sync issues that I should review? Should I capture additional diagnostic data (e.g., specific console logs, HealthKit database states)? Is unpairing/re-pairing expected to resolve this, or would that indicate a deeper architectural issue? Additional Context: Apple Watch appears in Settings > Bluetooth as connected Can successfully change watch faces from iPhone Notifications, Messages, and calls work normally No previous sync issues prior to watchOS 26.0.2 Senior Apple Support advisor escalation completed; awaiting engineering review This appears to be a regression introduced in watchOS 26.0.2. Any guidance on additional diagnostics or confirmation of a fix in upcoming builds would be appreciated.