Where is this new setting found?
This the sound one? To me it looks like it’s just on. In Sounds & Haptics, right under the Silent Mode toggle it says “Silent mode will not mute alarms and timers while the Apple Watch is charging.” So, just looks like it’s gotta be charging, so no sleep tracking.
It's on your Apple Watch.
1. Open Sleep App on the Apple Watch.
2. Scroll down to the bottom (or rotate the dial until you get to the bottom screen).
3. Click on "Wake Up"
4. Scroll down to "Sound & Haptics" and click on it.
5. There you will find "Break Through Silence". Toggle the switch to "ON"