Hi!
A week ago my OG galaxy watch (dated july 2019) stopped to monitoring sleep and then started to overcount steps, even when i was sit, in bed, or in general "motionless" (the walking activity tracks the right amount of steps and chilometers, and the hrm seems working ok)...i've tried several times to reset the watch, reinstall samsung health and galaxy wearable (and the plugin) in my android phone, but nothing works (i always restored my datas). I've also tried to do the self tests in the hidden menu *#0*#: all passed but the barometer (in the alti-barometer app i didn't see any measurement since years ago, while the altimeter worked only with gps of course)...do you have any suggests? Obv the watch is out of warranty 😞
Ps: i beat all my records doing 30k steps/day effortless 
@feduss: If your Galaxy Watch is registering steps while you're outside an activity, then please try heading to the Samsung Health app on the watch itself > Settings > Workout detection, and toggle this option off, or remove any activities that are added to this feature.
For the sleep monitor issue, please head to the Heart Rate Tracker screen > Tap the 3 dots in the top right > Swipe over to Auto HR Settings, and select 'Always'.
Let me know if this helps.
It may or may not be a coincidence but I started having problems from July 26th evening and, coincidentally, the galaxy wearable app was updated that day to version 2.2.50.22072061 ... planned obsolescence in view of the presentation of watch 5?
