Angular 5 reactive form set mat-checkbox to check : <p>I am trying to use mat-checkbox with reactive forms on Angular 5.1.2 and Angular Material 5.0.2.</p>

<p>Everything is working well except that when I use patchValue({amateur: [false]) it is still checked.  What is weird is I have other forms where I am doing the same thing and they work fine.  It also isn't just the amateur checkbox, it is all the checkboxes are checked.  Just using "amateur" as an example.</p>

<p>The formControl amateur.value is always false.  However once the patched value is executed, the control is checked.</p>

<p>What am I missing?</p>

<p>HTML5</p>

<pre><code> &lt;form [formGroup]="showClassGrp"&gt;
   &lt;mat-checkbox id="amateur" class="amateur" color="primary" 
      formControlName="amateur"&gt;Amateur&lt;/mat-checkbox&gt;
 &lt;/form&gt;
</code></pre>

<p>TypeScript</p>

<p>FormBuilder works and display is correct.</p>

<pre><code>this.showClassGrp = this.fb.group({

  ...
  amateur: [false],
  ...
});
</code></pre>

<p>patch showClassGrp and all the checkboxes are checked even thou the formControl value for them are false.  </p>

<pre><code>    this.showClassGrp.patchValue({
      className: [this.showClass.className],  //this works
      amateur: [false],  // this changed the display to checked.
      ...
});
</code></pre>
