When Im flying my mavic air the mph on app wont work. The miles per hour reads 0. How do I fix this?

Hi there, our apologies for the inconvenience. I would suggest you back up your files and sync your flight records and then reinstall the APP. May I know what mobile device, android/ios version and DJI Go 4 app version you are using? Click on "Reply" so that I can receive a notification from your response. Thanks for your support.