If the icon of your device in SteamVR Status is signaling green than the tracking is not working. If this happens your headset will lose tracking and then the display will go grey. If your HTC Vive Motion Tracking Boxes are not recognized follow the steps in this tutorial to solve this problem. This are the required steps:
■ For your base stations to work right and to track each other you should check if you have set up them correctly. Their position should be at least 6.5 feet away from each other, approximately above head height. The maximum distance that should be between the base stations is 5 meters ( 16 feet). Angle the base stations 35-40 degrees down, they should point to your play area.
■ Make sure that they have unobstructed view of the other base station, and your bases are correctly powered and synced. If everything is in the right way than the LEDs of the stations will be green.
■ If the cable connections are not right, and maybe are loose, can also be a reason for tracking issues. Check all the connections at the headset and make sure that the PC and the link box are secure.
■ Reflective surfaces can also cause tracking issues. If it happens to lose tracking or your motion controllers float away while you use them in VR, try solving this by covering the reflective surfaces in your Virtual Reality area.
■ Sometimes your front facing camera can cause some problems, while using it in VR. Solve this by lowering the bandwidth of the camera in SteamVR – Settings – Camera, or just disable the front camera.