When you start Nuggets for the first time it'll ask you to grant access to your location. Which makes sense in case you want to record a track for hiking, jogging, biking, driving or whatever else it is for you.
So you pressed GRANT LOCATION PERMISSION. At this point in time iOS only offers permissions "when using the app" at maximum.
But when you record a track usually you lock your mobile, put it in your pocket and set off. The moment you lock your mobile, technically, you don't use the app anymore, hence there will be no track or only a part of it.
To be able to record tracks while your mobile is locked, Nuggets needs location permissions "Always".
At some point in time the app will automatically ask for this permission. But this might be too late, if you start tracking right away.
To ensure your tracks get recorded completely from the beginning
- go to the settings of your iPhone,
- search for the settings for Nuggets,
- and change the location permissions to "Always".