User ID returned as 0 for non-admin users when logged in to the site- Drupal

I have a dashboard controller where I show the dashboard to users who are not anonymous. My controller code is as below:

class DashboardController extends ControllerBase {  
    protected $currentUser;

    /**
     * {@inheritdoc}
     */
    public function __construct(AccountProxy $current_user) {
        $this->currentUser = $current_user;
    }

    //HERE IS WHERE THE PROBLEM IS. FOR NON-ADMIN USERS, THE USERID IS RETURNED AS 0
    public function access(AccountInterface $account) {
      dd($this->currentUser);
      if (!$this->currentUser->isAuthenticated()) {
            return AccessResult::forbidden();
        } else {
            return AccessResult::allowed();
        }

    //FUNCTION TO DISPLAY DASHBOARD
    public function accessDashboard(AccountInterface $account) {
    $current_user = $this->currentUser;
      $roles = $current_user->getRoles();
      $current_user_record = \Drupal\user\Entity\User::load($current_user->id());
      if (!$current_user->isAuthenticated()) {
        return AccessResult::forbidden();
      }
      if ($current_user->hasPermission('view school dashboard')) {
        //SHOW THE ASSOCIATED SCHOOL NAMES DASHBOARD
      } 
      return AccessResult::forbidden();
    }
}

Screenshot of what I see when logged in as a non-admin user:

When logging in as an Administrator, I can clearly see the user ID and details as below:

any help on how to handle this problem?