Hi @Spinal
The easiest way is to use the get_field function to load any data (even in the save_post action!)
Make sure you run your code AFTER ACF has saved, like so:
<?php
add_action('acf/save_post', 'function_name', 20);
function function_name( $post_id )
{
$new_val = get_field('field_name', $post_id);
}
?>
