The icon on the screen sometimes does not work while in flight. I'm using an IPhoneXR to run the app. I found this today. Go to Settings,Privacy,Location Services,System Services and make sure the toggle is on (green) for compass calibration and motion calibration & distance. I haven't flown yet due to rain, but the arrow was working inside the house. I'll try it for real when the rain stops. Hope this may help for any having this problem.
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