phonegap-plugin-push on("notification") event is not firing when app is in background

I am using following plugin for push notification in Ionic2

http://ionicframework.com/docs/native/push/

Expected Behaviour: When app is closed, And notification received, And when user tap the notification, on("notification") event should fire after app opens.

Actual Behaviour: I am getting notification successfully. But When Application is in background or closed, at that time when I receive notification and I tap the notification, on("notification") event is not firing.

Cordova version 7.0.1 Android version 6.2.3

My code:

this.platform.ready().then(() => {
    this.pushsetup();
});

private pushOptions: PushOptions;
private pushObject: PushObject;
pushsetup() {
    // to check if we have permission
    this.push.hasPermission()
        .then((res: any) => {
            if (res.isEnabled) {
                console.log('We have permission to send push notifications');
                // configuration of push notification
                this.pushOptions = {
                    android: {
                        senderID: 'XXXXXXXXXXX',
                        icon: 'icon_notification'
                    },
                    ios: {
                        alert: 'true',
                        badge: true,
                        sound: 'false',
                        senderID: 'XXXXXXXXXXX'
                    },
                    windows: {}
                };
                this.pushObject = this.push.init(this.pushOptions);

                // attach push events
                this.storage.get('isPushRegistered')
                    .then(isPushRegistered => {
                        if( !isPushRegistered ){
                            this.pushObject.on('registration').subscribe((registration: any) => {
                                console.log('Device registered', registration)
                                this.storage.set('isPushRegistered', true)
                            });
                        }
                    })


                this.pushObject.on('notification').subscribe((notification: any) => {
                    console.log('Received a notification', notification)
                });
                this.pushObject.on('error').subscribe(error => console.error('Error with Push plugin', error));
            }
        });
}

So, on my code, you can see this.pushObject.on('notification') event. that is not firing when app is closed.

Thank you for your time and support.