Direct answer
Missing activity can follow loose fit, wrist-detection settings, paused workout, calibration or Health permission—not necessarily a dead sensor.
What this covers
- The observed symptom matches this record
- Customer-accessible settings, connections and external components
- Diagnosis before reset, deletion or component replacement
What it does not cover
- ×A model-specific error code with a different documented meaning
- ×Internal electrical, battery-cell, gas, refrigeration or sealed-component repair
- ×A guarantee that every model exposes the same control label
Capture the exact symptom
ReversibleCheck fit, wrist detection, Health permissions and whether heart rate/movement is recorded during a short walk.
Run the smallest isolation test
ReversibleRestart both devices, update software and calibrate with an outdoor walk when GPS conditions are good.
Correct only the proven cause
ReversibleCorrect personal details/permissions and keep the watch snug but comfortable during activity.
Verify before changing anything else
ReversibleRecord a 15-minute walk and confirm minutes, calories and steps sync to Health.
Evidence ledger
Sources behind this answer
Visible sources support the visible claims. Home Product Support records the publisher, the fact used and the review date; community reports can suggest an issue but do not become a published fact on their own.
Exact questions
Common follow-ups
What should I check before resetting anything?+
Check fit, wrist detection, Health permissions and whether heart rate/movement is recorded during a short walk.
What is the safest isolation test?+
Restart both devices, update software and calibrate with an outdoor walk when GPS conditions are good.
When should I stop troubleshooting?+
Seek service for sensor burns, cracked back glass, swelling or no heart-rate reading on multiple wrists.
Answer for the exact device and software version shown above.