Angular 2 does not update GroupGroup value automatically (enabled)

Question

I use the recently released 2.0.0 Angular, basically I have a component that initializes the values ​​of my form template, which consists of an input text field, and formArray from a FormGroup with two input text fields.

When initialization is done, the binding works fine, but when I click the new FormGroup on formArray, the form value does not reflect the newly added element until I make some change to the value in some text box that was originally bound. Why is this behavior and how can I get the value of the form if the dynamic addition of FormGroup is added?

My component and template code:

//initialize the form values
//this_fb is the form builder
setControlsValues(){
  
   this.form_band = this._fb.group({

		name : [ 'test', [ Validators.required ] ],
		bands : this._fb.array([

			this._fb.group({

				name : [ 'band 1', [ Validators.required] ],
				score : 10
			}),
			this._fb.group({

				name : [ 'band 2', [ Validators.required] ],
				score : 8
			})
		])
   });  
}
  
//push a new FormGroup when user click button
addBand(){
  
  this.form_band.controls.bands.controls.push( 

    this._fb.group({

      name : [ '', Validators.required ],
      score : 0
    })
  );
}

<form [formGroup]="form_band" validate="off">
	<div class="form-group">
		<label for="name">Name:</label>
		<input type="text" class="form-control"  formControlName="name" autocomplete="off">
	</div>
	<div class="form-group" >
		<h4>Bands</h4>
		<div formArrayName="bands">
			<div *ngFor="let band of form_band.controls.bands.controls; let i=index">
				<div [formGroupName]="i">
					<input type="text" class="form-control" formControlName="name">
					<input type="text" class="form-control" formControlName="score">
				</div>
			</div>
		</div>
		<button type="button" class="btn" (click)="addBand()">Add band</button>
	</div>

Run code

solvable

, .

addBand :

addBand(){

  this.form_band.controls.bands.push( 

    this._fb.group({

      name : [ '', Validators.required ],
      score : 0
    })
  );
}