title: ngIf inside NgFor not working
body: <p>I can't get this two <code>ng-container</code>-conditions inside <code>ion-item</code> get to work:</p>
  
  <pre><code>&lt;ion-list *ngIf="slide.options"&gt;
      &lt;ion-item *ngFor="let option of slide.options"&gt;
          &lt;ng-container *ngIf="option.type === 'boolean'"&gt;
              &lt;ion-label&gt;
                  &lt;h2 *ngIf="option.title" [innerHTML]="option.title"&gt;&lt;/h2&gt;
                  &lt;p *ngIf="option.description" [innerHTML]="option.description"&gt;&lt;/p&gt;
              &lt;/ion-label&gt;
              &lt;ion-toggle *ngIf="option.checked !== undefined || option.disabled !== undefined" [disabled]="option.disabled" [checked]="option.checked"&gt;&lt;/ion-toggle&gt;
          &lt;/ng-container&gt;
          &lt;ng-container *ngIf="option.type === 'range'"&gt;
              &lt;h2 *ngIf="option.title" [innerHTML]="option.title"&gt;&lt;/h2&gt;
              &lt;p *ngIf="option.description" [innerHTML]="option.description"&gt;&lt;/p&gt;
              &lt;ion-range *ngIf="option.min !== undefined || option.max !== undefined" [min]="option.min" [max]="option.max" [step]="option.steps" pin="true" snaps="true"&gt;
                  &lt;ion-label range-left&gt;{{option.min}} {{option.unit}}&lt;/ion-label&gt;
                  &lt;ion-label range-right&gt;{{option.max}} {{option.unit}}&lt;/ion-label&gt;
              &lt;/ion-range&gt;
          &lt;/ng-container&gt;
      &lt;/ion-item&gt;
  &lt;/ion-list&gt;
  </code></pre>
  
  <p>They are always seen as false. This results in an empty space:</p>
  
  <p><a href="https://i.stack.imgur.com/uJrtp.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/uJrtp.png" alt="Empty ion-items in ion-list"></a></p>
  
  <p>But in this way (or when adding the same conditions directly to the <code>ion-toggle</code> and <code>ion-range</code>-elements) it was nearly working (except that the <code>ngIf</code> on <code>ng-container</code> again was always false, while the <code>ngIf</code> on <code>ion-label</code> was executing fine):</p>
  
  <pre><code>&lt;ion-list&gt;
      &lt;ion-item *ngFor="let option of slide.options"&gt;
          &lt;ion-label *ngIf="option.checked !== undefined || option.disabled !== undefined"&gt;
              &lt;h2 *ngIf="option.title" [innerHTML]="option.title"&gt;&lt;/h2&gt;
              &lt;p *ngIf="option.description" [innerHTML]="option.description"&gt;&lt;/p&gt;
          &lt;/ion-label&gt;
          &lt;ng-container *ngIf="option.min !== undefined || option.max !== undefined"&gt;
              &lt;h2 *ngIf="option.title" [innerHTML]="option.title"&gt;&lt;/h2&gt;
              &lt;p *ngIf="option.description" [innerHTML]="option.description"&gt;&lt;/p&gt;
          &lt;/ng-container&gt;
          &lt;ion-toggle *ngIf="option.checked !== undefined || option.disabled !== undefined" [disabled]="option.disabled" [checked]="option.checked"&gt;&lt;/ion-toggle&gt;
          &lt;ion-range *ngIf="option.min !== undefined || option.max !== undefined" [min]="option.min" [max]="option.max" [step]="option.steps" pin="true" snaps="true"&gt;
              &lt;ion-label range-left&gt;{{option.min}} {{option.unit}}&lt;/ion-label&gt;
              &lt;ion-label range-right&gt;{{option.max}} {{option.unit}}&lt;/ion-label&gt;
          &lt;/ion-range&gt;
      &lt;/ion-item&gt;
  &lt;/ion-list&gt;
  </code></pre>
  
  <p>What am I doing wrong?</p>