I figured it out. I just switched the_field('mm_restaurant_name', 'option'); to get_field('mm_restaurant_name', 'option'); and now it works just fine. Thank you for your help!
I decided to pull the data from wp_option table instead so that the client will have an easy to find place to update contact information.
Now, I have tried many variations on this. The variable is getting the data from option but the field is not updating. As you can see I wan this to work with several fields but I’m starting with just the name because I cannot even get that to work. Any idea what I’m doing wrong here?
function add_contact_info_to_post( $post_id ) {
$mm_restaurant_name = the_field('mm_restaurant_name', 'option');
$mm_phone = the_field('mm_phone', 'option');
$mm_email = the_field('mm_email', 'option');
$mm_location = the_field('mm_location', 'option');
$field_key = 'field_56e5f9f891134';
update_field($field_key, $mm_restaurant_name);
}
add_filter( 'acf/save_post', 'add_contact_info_to_post' );