For anyone with a similar issue, I created a work-around for this. I created a blank, normal drop down menu with ACF and dynamically loaded the values into the dropdown using a function within functions.php. You can see an example of this on this page: http://www.advancedcustomfields.com/resources/dynamically-populate-a-select-fields-choices/. I then substituted their example with a normal loop to load in my scientists into the $field[‘choices’] array.
Search & Filter Pro picks up plain drop down menus just fine, so this worked well for me.
Here is the code I put in my functions.php in case it helps anyone:
function my_acf_load_field( $field ) {
$field['choices'] = array();
$sciArgs = array(
'post_type' => 'scientists'
);
$sciQuery = new WP_Query($sciArgs);
if ($sciQuery->have_posts()) : while ($sciQuery->have_posts()) : $sciQuery->the_post();
global $post;
$field['choices'][$post->post_name] = get_the_title();
endwhile; endif;
return $field;
wp_reset_postdata();
}
add_filter('acf/load_field/name=publication_person','my_acf_load_field');
.
