异步管道不适用于主题

我在服务中具有以下BehaviorSubject:

I have the following BehaviorSubject in a service:

  isAuthenticated = new BehaviorSubject<boolean>(false);

我正在组件中按如下方式使用它:

And I am using it as follows in a component:

  authenticated: Observable<boolean>;

  constructor(private accountService: AccountService) { }

  ngOnInit() {
    this.authenticated = this.accountService.isAuthenticated.asObservable();
  }

在模板中，我做类似的事情:

And in the template I do something like :

  <li class="login-button" *ngIf="!authenticated | async">
    <a (click)="authenticate()">Log in</a>
  </li>
  <li *ngIf="authenticated | async">
    <a>Logged in</a>
  </li>

问题是我看不到这两个li中的任何一个，尽管假设是第一个应该出现，因为我将Subject的初始值赋值为false.

The issue is that I dont see any of the two li, although the assumption is that the first one should appear since I am assigning the initial value of the Subject to false.

我在做什么错了?