Symptom

Suddenly, the value of the Move (Active Calories Burnt) is very low. The Move ring is much lower than normal while your other rings for Exercise and Stand are normal.

Suggested Resolution

Check the settings in Apple Health to see if your recorded weight has changed. Sometimes the weight can unexpectedly change to a very low value. In the example below the weight was recorded as 9kg which was far too low. After correcting the weight, the Move ring in Apple Heath returned to normal behaviour.