I would like for Private posts to be available to select in the Relationship field. I’ve tried to hook it with the following and although it seems to work (if I change ‘private’ to ‘draft’ it show the draft posts) the private posts just won’t show.
function my_acf_result_query( $args, $field, $post )
// eg from https://codex.wordpress.org/Class_Reference/WP_Query#Custom_Field_Parameters
$args['post_status'] = 'private';
// acf/fields/relationship/result - filter for every field
add_filter('acf/fields/relationship/query', 'my_acf_result_query', 10, 3);