Вот собственно и решение моей задачи, может кому пригодится:
<?php $services = get_field( 'services' ); ?>
<div class="service-features-nav">
<?php
$prev_post = get_adjacent_post(0, '', 0);
if( $prev_post && get_field('services', $prev_post->ID) == $services)
echo '<span class="nav-previous">← <a href="'. get_permalink($prev_post->ID) .'">'. $prev_post->post_title .'</a></span>';
$next_post = get_adjacent_post();
if( $next_post && get_field('services', $next_post->ID) == $services)
echo '<span class="nav-next"><a href="'. get_permalink($next_post->ID) .'">'. $next_post->post_title .'</a> →</span>';
?>
</div>