What should I do if the headset is not tracked?
Try the following methods to troubleshoot the issue:
- Make sure that the headset is placed inside the play area.
- If power on the headset was disconnected and reconnected, you need to also restart the SteamVR app.
- Try to disconnect and reconnect the HDMI cable to the HDMI port on your computer's graphic card.
- Restart the SteamVR app. If you still get an error, reboot your computer and reopen the SteamVR app.
For more information, you may refer to the 
SteamVR Troubleshooting page.