In order to pair the trackle sensor with the smartphone via Bluetooth, the “location services” or “location info” in Android must be activated.
This is how it currently works with Google: the Bluetooth services and the location services are stored on one chip – that’s why Bluetooth only works properly if location services or location info are active (not the other way round, incidentally: location services also work without Bluetooth).
To establish the connection between smartphone and sensor, you have to
allow access to your location services / location info when starting the trackle app for the first time and
keep the location services / location info activated when using the trackle app
trackle itself does not use your location data, does not store it and doesn’t do anything else with it. It only serves to activate the so-called coarse locations, that, in broad terms, match you to a radio cell.