Trying to change view from within an alert gives a black screen

Ionic Framework ionic-v3
1

Im trying to change to view within an alert as below. However when I try to change the screen the transition occurs but only a black screen is shown. Calling the this.nav.push(TemplateTabs); works fine outside of the alert so I imagine that its a problem with the way I’m using this.nav or the scope of nav within the alert.

    alert.addButton({
          text: "Ok",
          handler: data => {
            this.testRadioOpen = false;
            // send the user to the tabs page
            console.log(data);
            if (data) {
              this.params["templateName"] = data;
              this.nav.push(TemplateTabs);
            } else {
              // alert to pick an option
            }
          }
        });

Any advice on how to use the button to change views would be awesome.