Order by random not work wordpress anymore

recently i found orderby=rand not work. even my old wordpress theme which was work before after update wordprss not work any more. i tried many way to but seems all same.

<?php $my_query = new WP_Query('category_name=products&orderby=rand&showposts=5'); ?>

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

      <li>

        <a href="<?php
    $url = get_post_meta($post->ID, 'productURL', true); 

	if ($url) {
	    echo "$url";
	}
?>"  target="_blank"><?php  the_post_thumbnail() ?>

        <h2>

          <?php the_title(); ?>

        </h2>

       </a></li>

      <?php endwhile; ?>

above simple random post it was work before fine now don’t

<?php $testo_query = new WP_Query('category_name=testimonials&orderby=rand&showposts=1'); ?>
      <?php while ($testo_query->have_posts()) : $testo_query->the_post(); ?>
      <?php the_content(); ?>
      <div class="author">
        <?php the_title(); ?>
        <br>
        <?php the_field('position'); ?>
      </div>
      <?php endwhile; ?>

none is work.

guys any idea why not work.. how to make it work .