This is most likely caused by a connection problem between the app and the PIVOT sensors.
If you run into this:
- Restart the sensor marked H by holding the power button down for 2 seconds, releasing, then holding it down again for 2 seconds.
- You will probably also need to go the Wi-Fi settings on your iPad device and make sure the PIVOT network is selected.
Once you've done these two things, the PIVOT Tennis app should start displaying your movements again.