Not Able to List CPT Based on Taxonomy Term

Check this code:

<?php
    $custom_terms = wp_get_post_terms($post->ID, 'service_tax');
$count = count($custom_terms);
if ( $count > 0 ) {
    foreach($custom_terms as $custom_term) {
    $args = array('post_type' => 'services_cpt',
    'tax_query' => array(
                            array(
                                    'taxonomy' => 'service_tax',
                                    'field' => 'slug',
                                    'terms' => $custom_term
                                  ),
                        ),
    );

    $loop = new WP_Query($args);
    if($loop->have_posts()) {
        echo '<div class="col-md-4">';
        echo '<a class="item-box" href="'.get_permalink().'">'.get_the_title().'</a>';
        echo '</div>';
        while($loop->have_posts()) : $loop->the_post();
    endwhile;
}
}
}
?>