I have downloaded this app several times in an attempt to get it to track my miles. This app does not track it consistently and sometimes completely misses entire days.
We'll need to make sure that you've turned on your phone's location to Always if you're using iOS. If you're using an android phone, set the location to Allow all the time. Then, the physical activity permission is set to Allow.
This way, the app will consistently track miles.
If you want to categorize your mileage after a trip, you may follow the steps in these articles: