WooCommerce : display products in a tag. Add to your theme functions.php file

product-tag.php

  /**
   * List products in a product tag shortcode
   * Useage : [product_tag tag="foo"]
   */
  add_shortcode( 'product_tag', 'woocommerce_product_tag' );
	function woocommerce_product_tag( $atts ){
		global $woocommerce, $woocommerce_loop;

	  	if ( empty( $atts ) ) return;

		extract( shortcode_atts( array(
			'per_page' 		=> '12',
			'columns' 		=> '4',
		  	'orderby'   		=> 'title',
		  	'order'     		=> 'desc',
		  	'tag'			=> ''
			), $atts ) );

		if ( ! $tag ) return;

		// Default ordering args
		$ordering_args = $woocommerce->query->get_catalog_ordering_args( $orderby, $order );

	  	$args = array(
			'post_type'			=> 'product',
			'post_status' 			=> 'publish',
			'ignore_sticky_posts'		=> 1,
			'orderby' 			=> $ordering_args['orderby'],
			'order' 			=> $ordering_args['order'],
			'posts_per_page' 		=> $per_page,
			'meta_query' 			=> array(
				array(
					'key' 			=> '_visibility',
					'value' 		=> array('catalog', 'visible'),
					'compare' 		=> 'IN'
				)
			),
			'tax_query' 			=> array(
		    	array(
			    	'taxonomy' 		=> 'product_tag',
					'terms' 	=> array( esc_attr($tag) ),
					'field' 	=> 'slug',
					'operator' 	=> 'IN'
				)
		    )
		);

		if ( isset( $ordering_args['meta_key'] ) ) {
	 		$args['meta_key'] = $ordering_args['meta_key'];
	 	}

	  	ob_start();

		$products = new WP_Query( $args );

		$woocommerce_loop['columns'] = $columns;

		if ( $products->have_posts() ) : ?>

			<?php woocommerce_product_loop_start(); ?>

				<?php while ( $products->have_posts() ) : $products->the_post(); ?>

					<?php woocommerce_get_template_part( 'content', 'product' ); ?>

				<?php endwhile; // end of the loop. ?>

			<?php woocommerce_product_loop_end(); ?>

		<?php endif;

		wp_reset_postdata();

		return '<div class="woocommerce">' . ob_get_clean() . '</div>';
	}