Back button not showing when coming from nested pages (tabs)

Please try this:

<ion-view>
  <ion-pane>
    <ion-tabs class="tabs-top">
      <ion-tab title="Home">
        <!--Tab content goes here-->
      </ion-tab>
      <ion-tab title="About">
       <!--Tab content goes here-->
      </ion-tab>
    </ion-tabs>
  </ion-pane>
</ion-view>