I'm trying to output content from an Advanced Custom Fields (ACF) in my wordpress theme. At the moment though, all I'm getting is the plain text content from the ACF inside double quotation marks, not inside the div and h1 tags.

The code is copied from another theme I made where it worked, which makes me think something is interfering with it somewhere?

<?php $process_title = the_sub_field('process_title'); ?>

<?php if(!empty($process_title)) : ?>
    <div class="process-title">
        <h1 class="process-heading">
            <?php echo $process_title; ?>
        </h1>
    </div>
<?php endif; ?>