Causes of iPhone GPS Not Working
Some settings on the iPhone intentionally prevent GPS from working. Other causes for GPS not working are a weak signal, outdated maps data, or hardware failure. Although iPhone GPS issues are not common, they can occur after you update the iOS. Most of the solutions to the lack of a GPS signal are related to settings that are easy to fix. Most of the fixes for an iPhone GPS problem are related to settings and are easy to try. If none of the above fixes work, you might have a hardware problem, which is best diagnosed and repaired by Apple or an authorized Apple service provider. Search Apple’s online support site if you want to continue to try to fix it yourself. Otherwise, make an Apple Genius bar appointment and take your iPhone to an Apple Store.
Close that app and reopen it. Check the App Store to confirm you are running the most recent version of the app. Confirm Location Services are turned on for that particular app. Delete it from the phone and reinstall it from the App Store.