Ionic virtualscroll shows only the first 5 items

I’m not sure , if it’s a bug within Ionic or I’m doing something wrong here, all am trying to achieve is virtualscroll with ion-img , here is the code:-

generate an array of 100 image-links

posts: Array<any> = [];
  constructor(public navCtrl: NavController, public navParams: NavParams, private http: Http) {
    for (let i = 0; i < 100; i++)
      this.posts.push('' + i);

and the html:-


  <ion-list [virtualScroll]="posts" approxItemHeight="150px" bufferRatio="1">

    <ion-item *virtualItem="let post;">
        <div style="width:100%;height:150px">
          <ion-img width="100%" height="150px" cache="true" [src]="post"></ion-img>
            Nine Inch Nails Live
            The most popular industrial group ever, and largely responsible for bringing the music to a mass audience.



and it’s only showing/rendering the first 5 posts , is there something missing or doing it wrong here?