Mask Group with different devices resolutions

Hello.

We are using a MaskGroup to round Poster images in our app. This works fine in our FHD Roku Express devices but when we try in Roku Ultra or Roku Express 4K the mask is applied only to a small portion to the image, the code look like this:

 <MaskGroup id="roundedMask" maskUri="pkg:/images/mask/horizontalCard.png">
            <Poster
                id="HorizontalCardPoster"
                width="350"
                height="197"
                loadDisplayMode="scaleToZoom"
                translation="[0,0]" />
        </MaskGroup>