title: Some material icon doesn't show in production
body: <p>I don't know why but only in production some material icon doesn't appear, as you can see from the image the first icon is missing:</p>
  
  <p><a href="https://i.stack.imgur.com/cqfbU.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/cqfbU.png" alt="enter image description here"></a></p>
  
  <p>here's the code:</p>
  
  <pre><code> &lt;mat-nav-list&gt;
     &lt;a mat-list-item routerLink="/dashboard" matTooltip="dashboard"&gt;
       &lt;mat-icon matListIcon&gt;bar_chart&lt;/mat-icon&gt;
     &lt;/a&gt;
     &lt;a mat-list-item (click)="routeToContacts()" matTooltip="contacts"&gt;
       &lt;mat-icon matListIcon&gt;people&lt;/mat-icon&gt;
     &lt;/a&gt;
  </code></pre>