Bug when scroll up

[Saulmarti]

When I scroll down everything is perfect and fluid, however the moment I scroll up it loads all the items and the events stop working.

<virtual-scroller class="w-100 h-100" #scroll [items]="estrenos" (vsEnd)="loadData($event,'estrenos')">
         <app-portada class="col-6 p-1 d-inline-block" *ngFor="let item of scroll.viewPortItems" [rout]='"s"' [seccion]='"estrenos"'></app-portada>
</virtual-scroller>

The data is loaded 10 by 10 from a call to an api.
Does anyone have any idea why it might be?

Thanks !