1. Watch Pro only records heart rate data when it is on your wrist. When Watch Pro is not on your wrist, there will be gaps in the data, which is normal. 2. If Watch Pro is worn loosely or incorrectly, or if the heart rate detection sensor status is identified as "not worn," there will be gaps in the heart rate data. 3. If this does not solve the issue, press the button on the Watch Pro to enter Settings--System Menu, then click Restart. Or, press and hold the button, then click Restart and check again. 4. To experience the latest firmware features, you can upgrade the firmware to the latest version in the CMF Watch app. To do this, open the CMF Watch app, go to the Device page, and click Device Upgrade. 5. If the above steps do not resolve the issue, press the button on Watch Pro to enter Settings--System Menu. Click Reset. Then, check again to see if the issue is resolved. Ensure that the Watch Pro's case back is clean, dry, and free of debris before putting it on your wrist. Fit the monitoring unit snugly against your wrist.Do not stick protective film on the Watch Pro's case back, as this can interfere with the sensors and lead to inaccurate recording of or missing heart rate, blood oxygen, or sleep data.