按自定义元值分组WP用户查询

I'm trying to query WP Users and group them by billing_state, a custom meta key/value but I'm getting some unexpected results where it gives me some empty options but also is only returning one result per billing_state.

Based on some research on SO it was suggested I query all users and then create a new array where I can set the state as the array key then the user object as the value.

Here is what I tried:

add_shortcode('pro_pro_users','pro_pro_users'); 
function pro_pro_users(){

    global $wpdb; 
    $user_query = new WP_User_Query( array( 'fields' => 'all' ) ); 
    $users = $user_query->get_results(); 

    if (!empty($users)) { 
        $usersByState = array();
        foreach ($users as $user) {
            $usersByState[get_user_meta($user->ID, 'billing_state', true)] = $user;
        }

        foreach ($usersByState as $k => $v){ 
      if(!empty($v)) {
        echo '<li><h5>' . $k . '</h5>';
          echo '<ul>'; 
            foreach ($v as $user) {
               echo '<li><a href="' . get_author_posts_url($user->ID) . '">' . get_user_meta($user->ID, 'first_name', true) . ' ' . get_user_meta($user->ID, 'last_name', true) . ' (' . $user->display_name . ')</a></li>'; 
            }
          echo '</ul>';
        echo '</li>';
      }
        }

      echo '</ul>'; 
    } else { 
       echo 'No users found'; 
    } 
}

Here is what is happening (note the empty ones and only one per state although I know some of these have more than one

I've checked:

https://codex.wordpress.org/Class_Reference/WP_User_Query https://codex.wordpress.org/Database_Description#Table:_wp_users https://codex.wordpress.org/Function_Reference/get_users https://wordpress.stackexchange.com/questions/105937/group-posts-by-meta-key https://wordpress.stackexchange.com/questions/205427/group-posts-by-attachment-meta-key https://usersinsights.com/wordpress-user-meta-query/

What comes to my attention is that the following code will "override" each billing-state with the last user found:

  $usersByState = array();
  foreach ($users as $user) {
    $usersByState[get_user_meta($user->ID, 'billing_state', true)] = $user;
  }

From what I understood is that you should rather go for:

 $usersByState = array();
 foreach ($users as $user) {
    $billing_state = get_user_meta($user->ID, 'billing_state', true);
    if ($billing_state)
       $usersByState[$billing_state][] = $user;
 }

So by doing this you would collect several users for different states. Moreover this should take care of empty "states" as you described. Not sure whether this fully solves your issue but it might be a starting point for refining your function.