I’ve created an example Field Group with the same field names and the example won’t work. In my case, its a field group that’s a repeater and is being showed in the “options” page.
$rows = get_field(‘repeater_field_name’, ‘option’ ); // get all the rows
$rand_row = $rows[ array_rand( $rows ) ]; // get the first row
$rand_row_image = $rand_row[‘sub_field_name’ ]; // get the sub field value