您的代码运行良好。我在当地的WordPress上进行了测试，并按预期工作。

columns 属性是视觉表示，因此它不会影响显示的类别数。number 属性是检索到的类别数。我把它改为4，效果很好。

无论哪种方式，您都可以像这样优化代码：

function rand_product_categories( $atts ) {
    global $woocommerce_loop;

    // Get shortcode attributes and set default values
    $atts = shortcode_atts( array(
        \'number\'     => 10,
        \'orderby\'    => \'name\',
        \'order\'      => \'ASC\',
        \'columns\'    => \'4\',
        \'hide_empty\' => 1,
        \'parent\'     => 0,
        \'ids\'        => \'\'
    ), $atts );

    if ( isset( $atts[\'ids\'] ) ) {
        $ids = explode( \',\', $atts[\'ids\'] );
        $ids = array_map( \'trim\', $ids );
    } else {
        $ids = array();
    }

    $hide_empty = ( $atts[\'hide_empty\'] == true || $atts[\'hide_empty\'] == 1 ) ? 1 : 0;

    // get terms and workaround WP bug with parents/pad counts
    $args = array(
        \'orderby\'    => $atts[\'orderby\'],
        \'order\'      => $atts[\'order\'],
        \'hide_empty\' => $hide_empty,
        \'include\'    => $ids,
        \'pad_counts\' => true,
        \'child_of\'   => $atts[\'parent\']
    );

    $rand_product_categories = get_terms( \'product_cat\', $args );

    shuffle( $rand_product_categories );

    // add $atts[\'number\'] here
    $rand_product_categories = array_slice( $rand_product_categories, 0, $atts[\'number\'] );

    // child_of default value is 0, no need to check for parent
    /*if ( \'\' !== $atts[\'parent\'] ) {
        $rand_product_categories = wp_list_filter( $rand_product_categories, array( \'parent\' => $atts[\'parent\'] ) );
    }*/


/*
    // No need to check for hide empty, its already part of the query
    if ( $hide_empty ) {
        foreach ( $rand_product_categories as $key => $category ) {
            if ( $category->count == 0 ) {
                unset( $rand_product_categories[ $key ] );
            }
        }
    }
*/
 /*   if ( $atts[\'number\'] ) {
        $rand_product_categories = array_slice( $rand_product_categories, 0, $atts[\'number\'] );
    }*/

    $columns = absint( $atts[\'columns\'] );
    $woocommerce_loop[\'columns\'] = $columns;

    ob_start();

    // Reset loop/columns globals when starting a new loop
    $woocommerce_loop[\'loop\'] = $woocommerce_loop[\'column\'] = \'\';

    // Shuffle already done 
   // if ( shuffle($rand_product_categories) ) {
        woocommerce_product_loop_start();

        foreach ( $rand_product_categories as $category ) {
            wc_get_template( \'content-product_cat.php\', array(
                \'category\' => $category
            ) );
        }

        woocommerce_product_loop_end();
  //  }

    woocommerce_reset_loop();

    return \'<div class="woocommerce columns-\' . $columns . \'">\' . ob_get_clean() . \'</div>\';
}
add_shortcode( \'rand_prod_cat\', \'rand_product_categories\' );