This could be caused by a few things:
- You made some error during setup, or
- There's strong electromagnetic interference with the sensors
To be sure, the first thing to do is to start over:
- Turn off all the sensors
- Close the app
- Put all sensors back into the sensor box
- Reboot the app
- Choose your pro and stroke
- Choose Learn or Virtual Practice
- Let the app walk you through setup again.
When you go back through setup, here are some things to watch out for:
- When asked to lay the sensors flat, be sure they remain still.
- Make sure sensors are inserted straight into pockets. They should not be twisted or angled.
- Make sure your chest harness, glove, and armband are fitting snugly and are positioned correctly on your body
- Make sure the racquet sensor is completely snapped onto your strings. It should not jiggle or move at all as you swing.
- During body calibration, make sure your racquet is pointing in the exact same direction as your body