Use this snippet to change the Component Options column count when using the Product Thumbnails setting.

woocommerce-composites-product-thumbnails-cols.php

<?php
/**
 * Plugin Name: WooCommerce Composite Products - Component Options column count
 * Plugin URI: https://woocommerce.com/products/composite-products/
 * Description: Use this snippet to change the Component Options column count when using the Product Thumbnails setting.
 * Version: 1.0
 * Author: SomewhereWarm
 * Author URI: https://somewherewarm.gr/
 * Developer: Manos Psychogyiopoulos
 *
 * Requires at least: 3.8
 * Tested up to: 5.3
 *
 * Copyright: © 2017-2020 SomewhereWarm SMPC ([email protected]).
 * License: GNU General Public License v3.0
 * License URI: http://www.gnu.org/licenses/gpl-3.0.html
 */
 
// To use this snippet, download this file into your plugins directory and activate it, or copy the code under this line into the functions.php file of your (child) theme.
 
add_filter( 'woocommerce_composite_component_loop_columns', 'wc_cp_component_loop_columns', 10, 3 );

function wc_cp_component_loop_columns( $cols, $component_id, $composite ) {
	return 2;
}

I have the same problem it is not working. Tried plugin method and child theme methods but still no dice. Just displays one column. http://brucemoore.georgeyoung.pro/kiosk1/shop/all-necklaces/