KidPair tells you why — on the device card, on the map and by a notification: “location is off” (ask for “Location” to be turned on in the shade) or “supervision is stopped” (usually KidPair's notifications were turned off — open KidPair on the child's phone, it says what to turn on). If the “Parental control is working” notification is swiped away, it comes back and the location keeps arriving.
The location doesn't update although the phone is online
Protection off, a silent phone, no notifications. For the adult and the child