if ($wp_query->have_posts()) : while ($wp_query->have_posts()) : $wp_query->the_post();
    setup_postdata($post);
?>
    <!-- slide -->
    <li>
        <?php $posts = get_field('cf-rotator-rel');
        if( $posts ): foreach( $posts as $post): setup_postdata($post);
            $rotatorurl = get_permalink(); //grabs the permalink to the event just fine!
            $postid = $post->ID; //tested this, it's pulling the ID of the event!
            $startdate = eo_get_the_start('M j', $postid,null,$post->occurrence_id); //here's the bit
        ?>
        <a href="<?php if ($rotatorurl) { echo $rotatorurl; } else { echo '#'; } ?>" class="img-frame">
            <h2>EXHIBIT: <?php echo $startdate; //this isn't returning anything ?></h2>
        </a>
        <?php endforeach; wp_reset_postdata(); endif; ?>
    </li>
<?php
endwhile; endif;
$wp_query = null;
$wp_query = $temp;
wp_reset_query(); ?>