Form with radio buttons not submitted - angular5

Question

I have a form with two radio buttons which is enabled only when a checkbox is checked.
My problem is when I check the checkbox and click the submit button, the radio value is not getting posted. But after I click on the checkbox and then click on one of the radio buttons then the value is posted.
How to fix this issue?
This is the code I have tried:
HTML
<form [formGroup]="filterProductTargetForm" (ngSubmit)="onSubmitFilterDataList(filterProductTargetForm.value)">
<div class="row">
<div class="col-md-10">
<input type="checkbox" [ngModel]="isProductTypeChecked" formControlName="checkProductType" (change)="onProductTypeChange($event)" />
<label>Select A or B</label>
</div>
</div>
<div class="row">
<label class="col-md-2 uni-label"></label>
<div class="col-md-10 prduct-type-radio">
<fieldset [disabled]="!isProductTypeChecked">
<input type="radio" [checked]="isProductTypeChecked == true" value="A" formControlName="productTypeSelected" [(ngModel)]="productTypeSelected">
<span>B</span>
<br>
<input type="radio" value="B" formControlName="productTypeSelected" [(ngModel)]="productTypeSelected">
<span>B</span>
</fieldset>
</div>
</div>
<button class="uni-button def" [disabled]="!filterProductTargetForm.valid">OK</button>
</form>
TS
ngOnInit() {
this.filterProductTargetForm = this.formBuilder.group({
'checkProductType': '',
'productTypeSelected': ''
});
}
public filterProductTargetForm: FormGroup;
public isProductTypeChecked = false;
onProductTypeChange(event: any) {
this.isProductTypeChecked = !this.isProductTypeChecked;
if(!this.isProductTypeChecked)
this.filterProductTargetForm.controls['productTypeSelected'].reset();
}

Answer 1

First remove all ngModel from your template when using reactive forms.
When the checkbox value changes, in your onProductTypeChange function set the productTypeSelected value
this.filterProductTargetForm.controls['productTypeSelected'].setValue('A');
Working StackBlitz DEMO