Ion-alert with in confirmation part display not updated

With ionic 4.0.0 beta.15, (4.0.0.13 is the same, before I don’t know),
if I add a ion-alert with confirmation, in the confirmation part, I modify a binding variable in the DOM, but the modification of the display is not automatic.

To update the display, the user must interact, like change tabs or click on something in the page.

Maybe you have the same problem ?
Or maybe I don’t use it with the good way :
I do like this example : https://beta.ionicframework.com/docs/api/alert/#usage

In the html part, I have on a button this fonction :

(click)="deleteAlarmEvent($event)"

In the typescript part is :

async deleteAlarmEvent(event) {
const alert = await this.alertController.create({
      header: 'Delete Alarm !',
      message: 'Are you sure to want to <strong>delete</strong>?',
      buttons: [
        {
          text: 'Cancel',
          role: 'cancel',
          cssClass: 'secondary',
          handler: (blah) => {
            console.log('Confirm Cancel: blah');
          }
        }, {
          text: 'Okay',
          handler: () => {
            console.log('Confirm Okay delete');
            this.stateAdv = 'DELETED!';
          }
        }
      ]
    });
    await alert.present();
}

this.stateAdv is binding in the html part :

{{this.stateAdv}}

My info :
Ionic:

ionic (Ionic CLI) : 4.3.0 (/usr/local/lib/node_modules/ionic)
Ionic Framework : @ionic/angular 4.0.0-beta.15
@angular-devkit/build-angular : 0.9.0-beta.3
@angular-devkit/schematics : 0.9.0-beta.3
@angular/cli : 6.2.5
@ionic/angular-toolkit : 1.0.0

Cordova:

cordova (Cordova CLI) : 8.0.0
Cordova Platforms : android 7.1.1
Cordova Plugins : cordova-plugin-ionic-keyboard 2.1.2, cordova-plugin-ionic-webview 2.1.4, (and 7 other plugins)

System:

Android SDK Tools : 26.1.1 (/Users/gregory/Library/Android/sdk/)
ios-deploy : 1.8.6
NodeJS : v10.13.0 (/usr/local/bin/node)
npm : 6.4.1
OS : macOS Sierra