cesium: label : HeightReference.CLAMP_TO_GROUND "An error occurred while rendering."

Today I update cesium 1.47 instaed 1.43. But when I add a label with “heightReference: Cesium.HeightReference.CLAMP_TO_GROUND”, the chrome reports me the text :

An error occurred while rendering. Rendering has stopped. RuntimeError: Program failed to link. Link log: Could not pack varying v_logZ Note: Additional non-conformant packing restrictions are enforced on D3D9.

Error at new t (http://localhost:5000/libs/Cesium/1.47/Cesium.js:451:28517) at f (http://localhost:5000/libs/Cesium/1.47/Cesium.js:480:17965) at y (http://localhost:5000/libs/Cesium/1.47/Cesium.js:480:19679) at d._bind (http://localhost:5000/libs/Cesium/1.47/Cesium.js:480:20694) at G (http://localhost:5000/libs/Cesium/1.47/Cesium.js:508:913) at k.draw (http://localhost:5000/libs/Cesium/1.47/Cesium.js:508:4878) at n.execute (http://localhost:5000/libs/Cesium/1.47/Cesium.js:479:21080) at Ge (http://localhost:5000/libs/Cesium/1.47/Cesium.js:530:16825) at Xe (http://localhost:5000/libs/Cesium/1.47/Cesium.js:530:21309) at tt (http://localhost:5000/libs/Cesium/1.47/Cesium.js:530:26613)

my test code:

var viewer = new Cesium.Viewer('cesiumContainer', {
    terrainProvider: Cesium.createWorldTerrain()
});
viewer.scene.globe.depthTestAgainstTerrain = true;

var e = viewer.entities.add({
    position : Cesium.Cartesian3.fromDegrees(-122.1958, 46.1915),
     label : {
        text : 'Clamped to ground',
        heightReference : Cesium.HeightReference.CLAMP_TO_GROUND,
        horizontalOrigin : Cesium.HorizontalOrigin.CENTER,
        verticalOrigin : Cesium.VerticalOrigin.BOTTOM,
        fillColor : Cesium.Color.BLACK,
        showBackground : true,
        backgroundColor : new Cesium.Color(1, 1, 1, 0.7),
        backgroundPadding : new Cesium.Cartesian2(8, 4)
    }
});

viewer.trackedEntity = e;