Next/previous post not going in order

Hey guys,
I’ve been trying to add next/previous post buttons to my site using the below code:

/**
 * @snippet       Add next/prev buttons @ WooCommerce Single Product Page
 * @how-to        Get CustomizeWoo.com FREE
 * @sourcecode    https://businessbloomer.com/?p=20567
 * updated code with forum: https://generatepress.com/forums/topic/previous-and-next-buttons-in-woocommerce/#post-637396
 * @author        Rodolfo Melogli
 * @testedwith    WooCommerce 2.5.5
 */
 
add_action( 'woocommerce_before_single_product', 'tu_prev_next_product' );
function tu_prev_next_product(){
    echo '<div class="prev_next_buttons">';
        $previous = next_post_link( '%link', '&larr; Previous', true, '', 'product_cat' );
        $next = previous_post_link( '%link', 'Next &rarr;', true, '', 'product_cat' );
		echo $previous;
   		echo $next;
    echo '</div>';
}

But i’m having two problems:
1) I don’t think the products are being linked to in any discernable order – I want it to be sorted in the order the user has selected, i.e. on the category page you can choose the ordering such as ‘Sort by latest/popularity/price etc.’, but I fear it may be going by posted date

2) I can’t see the buttons appearing on some categories, such as in this one https://katecouragemusic.com/product-category/solos/

Can you please advise?

Thanks!

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