@prairiedog Wow! Well, I tried a million things. First, I tried downgrading, but it only put the watch in safe mode for several hours. Then I reinstalled the same firmware version. Multiple soft resets. Nothing. I did a hard reset, and it was useless. Then I went back to using my 9PP (disconnecting the Race S), on which sleep tracking worked. I went back to the Race S, still nothing. Then I adjusted the sleep time on the 9PP from 0.00 to 0.00 and went back to the Race S again. Nothing.
Finally, I reinstalled the app with the Race S connected, and magically, it worked. So I don’t know if it was a combination of factors or just the app reinstallation.