Angular 2 ngFor not rendering - angularjs

Question

I'm trying to use ngFor under a template and retrieve children to modify them later.
Here is my template:
<div (mouseenter)="showTooltip()" (mouseleave)="hideTooltip()" (mousedown)='onMouseDown($event)' class='slider slider-{{ orientation }}'>
<div class='slider-track'>
<div #trackLow class='slider-track-low' [ngClass]="{hide: (type === 'slider' || selection === 'none' || selection === 'after')}"></div>
<div #trackSelection class='slider-selection' [ngClass]="{hide: (selection === 'none')}"></div>
<div #trackHigh class='slider-track-high' [ngClass]="{hide: (selection === 'none' || selection === 'before')}"></div>
</div>
<div class="slider-tick-label-container" [ngClass]="{hide: labels.length === 0}">
<div #labelElements *ngFor="let label of ticksLabels" class="slider-tick-label">{{ label }}</div>
</div>
<div class="slider-tick-container" [ngClass]="{hide: ticks.length === 0}">
<div #tickElements *ngFor="let tick of ticks" class="slider-tick {{ handleType }}"> </div>
</div>
<div #tooltipMain class="tooltip tooltip-main {{ tooltipPosition }}" role="presentation">
<div class="tooltip-arrow"></div>
<div #tooltipMainInner class="tooltip-inner">Current value: {{ value }}</div>
</div>
<div #tooltipMin class="tooltip tooltip-min {{ tooltipPosition }}" role="presentation">
<div class="tooltip-arrow"></div>
<div #tooltipMinInner class="tooltip-inner"></div>
</div>
<div #tooltipMax class="tooltip tooltip-max {{ tooltipPosition }}" role="presentation">
<div class="tooltip-arrow"></div>
<div #tooltipMaxInner class="tooltip-inner"></div>
</div>
<div #minHandle tabindex="0" (keydown)="keydown(0, $event)" (focus)="showTooltip()" (blur)="hideTooltip()" class='slider-handle min-slider-handle {{ handleType }}' role='slider'></div>
<div #maxHandle tabindex="0" (keydown)="keydown(1, $event)" (focus)="showTooltip()" (blur)="hideTooltip()" class='slider-handle max-slider-handle {{ handleType }}' [ngClass]="{hide: type === 'slider'}" role='slider'></div>
</div>
Both ngFor are rended like this in DOM:
<div class="slider-tick-container">
<!--template bindings={}-->
</div>
In my component I try to retrieve elements with:
#ViewChildren('tickElements') private tickElements: QueryList<ElementRef>;
#ViewChildren('labelElements') private labelElements: QueryList<ElementRef>;
Both are undefined because of the rendering problem...
I try to remove the template and replace it by <div *ngFor="let i of [1,2,3,4]">{{i}}</div> and same problem !
The full code is available here: https://github.com/jaumard/ng2-bootstrap/blob/ticksLabels/components/slider/slider.component.ts#L15