no magnetometer sensor data events on the Fenix 5X

I registered a sensor data listener on the Fenix 5X but no events are fired. (or possibly events are fired and the magnetometer data is null)

        var options = {
            :period => 1,               // 1 second sample time
            :magnetometer  => {
                :enabled => true,       
                :sampleRate => 10    
            }
        };
        // Using the callback setup in Toybox.SensorHistory.SensorData
        Sensor.registerSensorDataListener(method(:magCallback), options);
Does anyone have a solution?