These Settings must be properly configured to keep Mobile Tracker Free working.
Info: A password may be required to access the application settings. If you have not changed, the default password is *1234*. More information about the application password here.
1) Settings => Apps & notifications => See all X apps => Wi-Fi => Data usage => Background data & Unrestricted data usage => Turn ON
2) Settings => Network & Internet => Data usage => Data saver => Turn OFF