fitness, heart rate, and workout apps stopped working last night (2/15/2023), watch series 4
Yesterday evening, after I took my watch off the charger, the fitness app stopped logging any activity. I didn't notice until bedtime, at which point I restarted the watch. After the restart, the fitness app shows nothing. Just a black screen when I start it. I've tried just restarting the app. Nothing. I've updated the watch (now at watch OS 9.3.1). Nothing.
The heart rate app has no history, and won't take a reading.
The workout app starts a workout (and reads my heart rate!), but dies when I end the workout. The usual summary screen appears, but the app dies before I can scroll to the end to hit the Dismiss button.
All of the other watch functions seem to be working normally. Just not these three apps. Which are very important to me!
I've also updated my phone (now at iOS 16.3.1, iPhone 11 Pro). Same behavior.
Any hints?
Apple Watch Series 4, watchOS 9