We discussed it in private mail, the solution was the following:
We have modified wp-related-items/wri_template/template-wri-woocommerce-loop-shop.php, and inserted these lines:
global $woocommerce_loop;
$options = get_option( 'wri_related_items___product' );
$woocommerce_loop['columns'] = $options['thumbnail_columns_number'];These lines was inserted after this line:
if ( ! defined( ‘ABSPATH’ ) ) exit; // Exit if accessed directly
These modification will be in the next release of Pro version.