If an object should be in front of you, but it’s behind you or wandering across the screen, try calibrating your device. First,, remove all magnets or metal cases with magnets that could be throwing off your GPS coordinates. Restart your device and check whether your location-based services are on properly and that you’ve given authorization to Stops to do so from your Locations Services settings, located in the Privacy area of your device. iOS users should turn on their Use True North settings from your Compass settings.