I have a CPT called Companies. I created an ACF relationship field called user_company that gets displayed in the Users profile page.

When a user registers, I have to go in and assign them to a company. I added the ACF field to the Users page admin column but I am unable to sort it. It currently sorts based on post_id and I have no idea how to sort it by post_title.

Here is the code I have so far:

// Add columns and data to Users admin page
add_filter( 'manage_users_columns', 'manage_users_columns_new_columns' );
function manage_users_columns_new_columns( $columns ) {
    $columns['user_comp any'] = 'User Company';
  return $columns;
}
add_filter( 'manage_users_custom_column', 'manage_users_custom_column_new_columns', 10, 3 );
function manage_users_custom_column_new_columns( $value, $column_name, $user_id ) {
    if ( $column_name == 'user_company' ) {
        $user_company = get_field('user_company', 'user_' . $user_id);
        $user_company_post = get_post($user_company);
        if( isset( $user_company_post ) ){
          return $user_company_post->post_title;
        } else {
          return '-';
        }
    }
    return $value;
}

// ACF/save_post to save title of User Company as another meta_value
function save_user_company_name ( $post_id ) {
  $user_company_id = get_field( 'user_company', $post_id );
  if ( $user_company_id ) {
    update_post_meta( $post_id, 'user_company_name', get_post_field( 'post_title', $user_company_id ) );
  }
}
add_action( 'acf/save_post', 'save_user_company_name', 20 );

// Sort columns on Users admin page
add_filter( 'manage_users_sortable_columns', 'register_sortable_columns_custom', 10, 1 );
function register_sortable_columns_custom( $columns ) {
    $columns['user_company'] = 'user_company';
  return $columns;
}
add_action( 'pre_get_users', 'pre_get_users_sort_columns_custom' );
function pre_get_users_sort_columns_custom( $query ) {
    if ( $query->get( 'orderby' ) == 'user_company' ) { // Currently sorts by post ID vs post title. Will need to add additional code: https://support.advancedcustomfields.com/forums/topic/admin-column-a-z-sorting-for-object-field/
        $query->set( 'orderby',  'meta_value' );
        $query->set( 'meta_key', 'user_company_name' );
  }

}

I added the acf/save_post portion based on answers I have found online but I don’t know how that works. I tried saving each Company posts as well as the Users assigned to a company. But when I try to sort on the admin page, everything blanks out. I’m not sure how to get this to work.