IOS: Stop moving navbar when scroll on Ionic 2

Question

I have a bottom navbar in my Ionic 2 app.

On IOS, the problem is that when the user scrolls this bottom navbar moves with the scroll, if the user scrolls up, the navbar moves up, and if the user scrolls down, the navbar moves down. But, when the scroll finishes, the navbar goes to its default position (bottom 0).

It's not happening on Android. It works perfectly, the user scrolls and the bottom navbar is always on bottom.

This is the part of the code:

<section no-shadow padding class="mainItemsContainer">
  <ion-grid id="navbar-grid">
    <ion-row>
      <ion-col>
       blabla items here
      </ion-col>
    </ion-row>
  </ion-grid>
</section>

And:

.mainItemsContainer {
    position: relative;
    padding-top: 2% !important;
    padding-bottom: 0.5% !important;

    ion-grid {
      position: fixed;
      bottom: 0;
      left: 0;
      padding-top: 3.3%;
      background-color: #FFF !important;

      ion-col {
        padding: 0 !important;
        position: relative;
        text-align: center;
      }
   }
}

Thank's in advance!