what I currently have, but doesn’t work is:
<div class="acf-map">
<?php
$featured_projects = get_field('locations_all');//relationship
if( $featured_projects ): ?>
<?php foreach( $featured_projects as $featured_project ):
$featured_project_id = $featured_project->ID;
$location = get_field('location');//field
?>
<div class="marker" data-lat="<?php echo $location['lat'], $featured_project_id; ?>" data-lng="<?php echo $location['lng'], $featured_project_id; ?>">
</div>
<?php endforeach; ?>
<?php endif; ?>
</div>
