Ion-fab not fixed in android 5

Ionic Framework ionic-v3
1

I use the following code for button fix in page

   <ion-fab bottom left fixed>
     <button ion-fab mini color="danger" (click)="content.scrollToTop()">
        <ion-icon name="arrow-dropup"></ion-icon>
     </button>
   </ion-fab>

this work correctly in android 4.4 and 6 to up.
but not work correctly in android 5 and 5.1.0(not fix)