fxFlex has no effects on elements

So, in my angular project Im using fxFlex in many places. I imported fxFlex in the module but in one place it is not working and I dont know why. This is my template code:

<div fxLayout="row" *ngIf="elementDescription$ | async as root">

    <div fxFlex="20%" *ngFor="let page of root.elements; index as i" >
        <app-card [elementDescription]="page" [index]="i" ></app-card>
    </div>

</div>

Am I missing here something? I am using NG Bootstrap in my project if thats relevant