if these are not getting any values then there is an issue with these fields
$post_type = get_sub_field('content_type');
$posts_per_page = get_sub_field('items_per_row');
are you sure these are the fields? Are they nested inside of something else like a group field or something?
Obviously row_order_and_qty has rows or nothing would happen so it has to be something about the sub fields.
