Do you experience that the Mileage Book app stops registering your mileage in the middle of a trip. This may be because your Android device is going into power-saving mode, which may result in access to the GPS being blocked. However, this can be avoided by turning off the battery optimization of the Mileage Book app.
By following this guide, you make sure that your Mileage Book app is never put in battery-saving mode.
Keep in mind that these steps may look different on other Android devices.
(in this example an HTC device is used)
From the Home screen, swipe up and then find and tap Settings.
Tap Menu button > Battery optimization.
Tap Not optimized > All apps to see the complete list of apps.
To turn off battery optimization in an app, tap the app name, and then tap Don't optimize > Done.