Please make sure that your app and watch firmware are on the latest version available, and your step goal is activated.
If the above did not help, it is highly advisable to reset the timepiece.
Reset: Please hold the 3 o'clock pusher for 10 seconds (or until you will feel the timepiece vibrating) the hour hand will begin to move. Then release and press it down again for another 10 - 15 seconds. The hands will stop at the 12 o'clock marker indicating that the reset was successful. Once the reset is complete, please proceed with pairing the timepiece as indicated in the manual.