Mapbox GL Issue with Updating Line Display

Question

I have a line that is drawn on the map. It is initially created in the IF section of the following code, and it is updated in the ELSE section. However, the UI is never update with the setData(). I have similar code with a polygon and it works fine. What is wrong?

if (!moDistanceSource) {
    moDistanceSource = {
        'type': 'FeatureCollection',
        'features': [{
            'type': 'Feature',
            'geometry': {
                'type': 'LineString',
                'coordinates': [[-120, 49], [-118, 40]]
            }
        }]
    };
    moMap.addSource('DistanceSource', {
        "type": "geojson",
        "data": moDistanceSource
    });
    moMap.addLayer({
        'id': 'DistanceLayer',
        'type': 'line',
        'source': 'DistanceSource',
        'layout': {
            "line-join": "round",
            "line-cap": "round"
        },
        'paint': {
            "line-color": "#888",
            "line-width": 3
        }
    });
    console.log('add distance layer');
}
else {
    moDistanceSource.features[0].geometry.coordinates = [[-110,59],[-108,50]];
    console.log('maDistancePoints', maDistancePoints);
    moMap.getSource('DistanceSource').setData(moDistanceSource);
}