title: *ngIf not working as expected with observable
body: <p>So I have these 2 buttons:</p>
  
  <pre><code>&lt;a class="router-link nav-item" routerLink="/login" *ngIf="!isLoggedIn$ | async"&gt;
    Login
  &lt;/a&gt;
  &lt;a class="router-link nav-item" (click)="onLogout()" *ngIf="isLoggedIn$ | async"&gt;
    Logout
  &lt;/a&gt;
  </code></pre>
  
  <p>And the logout button works perfectly, as soon as the user is logged in the button appears. But the login button never appears.</p>
  
  <p>This is the code behind the <code>isLoggedIn$</code>:</p>
  
  <pre><code>isLoggedIn$: Observable&lt;boolean&gt;;
  
  ngOnInit() {
    this.isLoggedIn$ = this.authService.isLoggedIn;
  }
  </code></pre>
  
  <p>AuthService:</p>
  
  <pre><code>private loggedIn = new BehaviorSubject&lt;boolean&gt;(false);
  
  get isLoggedIn() {
    return this.loggedIn.asObservable();
  }
  </code></pre>
  
  <p>Hope this is enough information and the problem is clear, thanks in advance!</p>