Nav Controller pop toolbar button disappears then reappears

I have a button in my ionic 2 footer. It slides ok with push but not with pop and a back transition. It disappears then reappears and doesn’t look great. How can I get it to slide like the forward transition does?

<ion-footer class="has-back-btn">
  <ion-toolbar class="no-padding transparent">
 <ion-buttons start>      
<button class="back-btn" tappable (click)="goBack()" ion-button icon-left>
 <i class="fa fa-chevron-left " aria-hidden="true"></i> Back
</button>
     </ion-buttons>
  </ion-toolbar>
</ion-footer>


 goBack() {
  
  var navOptions = {
      animation: 'ios-transition',
      direction: back,
      animate: true,
  };

  if(this.isModal == true){
      this.navCtrl.pop();
  }else{
     this.navCtrl.pop(navOptions);
  }
  }

here is a screen shot