The Android Operating System introduced a feature to attempt to improve battery life called "App Power Monitor" (see attached image for an example). As per the instructions on the phone, this will "stop these apps from draining your battery while you are not using them".
However, if enabled for Btracking, it will STOP the Btracking app from running, and thus stop it from reporting positions.
This is NOT an issue with the Btracking app, it is a feature of the Android operating system and will affect background apps including Facebook, Whatsapp and other background apps if enabled.
Our recommendation is DO NOT use the "Fix Now" battery save mode for Btracking. Another way to avoid this is to go into Development Options, then to Background Process Limit, and select Standard Background. This will keep the standard background applications open.