Hi Mario,

Please provide me with a product link so I can check it first.

Please add the custom code below. (How to add custom code? ↗):

add_action( 'wp_footer', function () {
    ?>
    <script type="text/javascript">
      (function($) {
        $(document).on('click touch', '.wooco-plus, .wooco-minus', function() {
          var $qty = $(this).closest('.wooco-qty').find('.qty');
          $qty.trigger('keyup');
        });
      })(jQuery);
    </script>
    <?php
}, 99 );

If it still doesn't work, please send me your website credentials (wp-admin link, username, and password) or create a dev/staging site with the same configurations so I can check and fix any issues.