Selecting an entity switch from 2D into 3D mode

I'm just playing around with CesiumJS. It is embedded in a little Angular Frontend and im loading entities from a Spring Backend.

I'm using 2D only ( at this time ).
When I'm selecting an Entity it's correct renderd ( setting the points pixelSize and the Color but the view switches from 2D into 3D.

// picking the position of a translucent primitive
    this.viewer.screenSpaceEventHandler.setInputAction(
      movement => {
        const pickedFeature = this.viewer.scene.pick(movement.position);
        console.log('pos:' + movement.position);
        if (!Cesium.defined(pickedFeature)) {
          // nothing picked
          console.log('nothing picked!');
          return;
        } else {
          const entity = this.ds.entities.getById(pickedFeature.id.id);
          entity.point.pixelSize = 15;
          entity.point.color = Cesium.Color.fromCssColorString('RED');
          console.log(entity.id);
// this.viewer.zoomTo(entity);
        }
        this.viewer.render();
        // const worldPosition = this.viewer.scene.pickPosition(movement.position);
      }, Cesium.ScreenSpaceEventType.LEFT_CLICK);

CesiumJS: 1.47.0
Chrome: 68.0.3440.106
Firefox: 61.0.1

Can anybody tell me, whats to do to keep 2D mode?

best regards
Harry

I’m having some trouble recreating this. Does it only happen when you set the pixelSize and color on click? Can you show the settings you initialize when you create the viewer?

If you can put together a running Sandcastle example of this issue that’ll help a lot too.