Background images are not loading

Ionic Framework ionic-v3
1

Hello everyone,
I’m trying to add a background image on my sidemenu
the main problem is that the image is loading sometimes, and sometimes not!
it’s really weird now I’ve been trying to fix for hours and I’m so tired, and none of the solutions on the forum helped me.

Editing my question:
it worked on chrome with ionic serve but when I do ionic serve --lab background image is not working.
My css:

.bg-image{

  --background: url('/assets/imgs/menubg1.png') no-repeat center center fixed;

  background: url('assets/imgs/menubg1.png') no-repeat center center fixed;

  -webkit-background-size: cover;

  -moz-background-size: cover;

  -o-background-size: cover;

  background-size: cover;

}

My html

<ion-content class="bg-image">

      <ion-list >

        <ion-list-header >

          <ion-thumbnail item-left>

            <img  src="assets/imgs/logo.png"/>

          </ion-thumbnail>

          <h3 style="font-family: 'Trebuchet MS', 'Lucida Sans Unicode', 'Lucida Grande', 'Lucida Sans', Arial, sans-serif;">How to fit</h3>

        </ion-list-header>

        <button    menuClose ion-item *ngFor="let p of pages" (click)="openPage(p)">

          <ion-icon [name]="p.icon" item-left></ion-icon>

            {{p.title}}

        </button>

      </ion-list>

    </ion-content>