When you choose this option in items field you should add only elements Resource Collections

Fill: Fills the entire card image area, cropping off pixels if image does not match the aspect ratio. Best for photos.

Pad: The entire image will fit the available space, padding the image with white or black background-color depending on your section BG color. Best for illustrations.

Icon: Use this option if the image you’re uploading is an icon. Icon’s will be displayed 64px wide and tall.

Circular: Circular image mask, centered text.

Original ratio (no cropping): Image will appear on original ratio