We found the solution. For iOS/watchOS 26, you MUST: Migrate from the legacy Watch dual-target to a single-target. Generate the watch face file within your TestFlight build and bundle it with your app; do not generate it in a development environment. This ensures the complications are associated with a valid App Store ID. This strict validation appears to be new in iOS/watchOS 26, as it was not present in iOS/watchOS 18. Reference: Sharing Apple Watch Faces.

iOS app share: watchOS app share:

Hello, I'm facing this issue on iOS/watchOS 26. Complications work in development(debug/release) but fail in TestFlight/App Store. Has anyone found a fix?

👍