I’m attempting to display custom columns that return the last modified date and the author that updated it.

function rh_custom_page_columns( $columns ) {
    $columns['last_modified'] = 'Last modified';
    $columns['modified_author'] = 'Modified by';
    return $columns;
}
add_filter('manage_pages_columns','rh_custom_page_columns');

function rh_custom_columns_date_author ( $column_id, $post_id ) {
    switch( $column_id ) {
        case 'last_modified':
            echo get_post_field('post_modified', $post_id);
            break;

        case 'modified_author':
            echo the_modified_author();
            break;
    }
}
add_action( 'manage_pages_custom_column','rh_custom_columns_date_author', 10, 2 );

the_modified_author() doesn’t return any value even though the author exists as a user. I’ve also tried get_the_modified_author() that outputs and empty value too.

How else can I display the author that modified the page (and not the author had originally published it)?

Researching it further, there seems to be a bug? with the function – https://wordpress.org/support/topic/get_the_modified_author-not-working/