Displaying Random Image from ACF Options Page [closed]

Just noticed the issue – since your ACF field is an options page, you need to pass the second argument options to get_field – add a bit of sanity checking too:

$rows = get_field( 'image_advert_repeater', 'options' );
if ( ! empty( $rows ) && is_array( $rows ) ) {
    // Your code
}