These Settings must be properly configured to keep CellTracker working.
1) i Manager => Permission management => Apps => « GPS » => Single permission settings => Turn ON All
2) i Manager => Data Monitor => Network management => « GPS » => Data network & WLAN => Turn ON
3) i Manager => Virus scan => Settings icon => Regular scan reminder => Turn OFF
4) Settings => Mobile network => « GPS » => Turn ON
5) Setting => Mobile network => Data-saving mode => Whitelist apps => GPS => Turn ON
6) Settings => Battery => High background power consumption => GPS => Turn ON