Apple’s update to Watch OS 1.0.1 was intended to improve the performance of several fitness-related functions, but also appears to have introduced a bug. Instead of the Apple Watch recording your heart rate every ten minutes, many users – including myself – are seeing large gaps in the data.
My readings for yesterday afternoon and evening, shown above, contain four gaps of more than an hour. Two of these gaps span times when I was cycling, when the data would have been most relevant. Users in an Apple Support Communities thread (via EverythingCafe) are reporting the same thing …
Some users are reporting that they see no heart rate reading at all unless they trigger it manually by opening the Glance. Continuous heart rate monitoring during a Workout also still seems to function correctly.
You can check your own readings in the Health app. First open the Apple Watch app and go to General > About and check the Version to make sure you are running 1.0.1, then open the Health app, touch the Health Data tab, then select Vitals > Heart Rate > Show All Data.
We’ve reached out to Apple and will update if we receive a response.