Hi Lukas,
As you use single_image
field, the field value is not an array (as it's only one image). So, please change to code to:
$image_id = isset( $group_values['exhb_gallery'] ) ? $group_values['exhb_gallery'] : null;
if ( $image_id ) {
$image = RWMB_Image_Field::file_info( $image_id, array( 'size' => 'large' ) );
echo '<img src="' . $image['url'] . '" width="' . $image['width'] . '" height="' . $image['height'] . '">';
}
Or if you really want to use a gallery, then please change the field type to image_advanced
and keep the code as it is.