Editing a users custom fields from a plugin action Craft 3

Does anyone know if there is a block on updating users form an action?

Trying to update a users custom field in craft 3 via plugin in the admin. The admin template calls an ajax call to the action when a drop-down is changed.

This works ok in the base of the plugin, but not in an action.

    public function actionUpdateuser()
    {
        // Update user data
        $userId = 67852;
        $user = Craft::$app->users->getUserById($userId);
        $user->setFieldValue('userCompanyName', 'New Name 2'); 
        $result = Craft::$app->elements->saveElement($user);

        return $result;
    }

The action fires ok and can return other things just does not update the user.

public function actionUpdateuser() {
    // Update user data
    $userId = 67852;
    $user = Craft::$app->users->getUserById($userId);
    $user->userCompanyName = 'New Name 2'; 
    $result = Craft::$app->getElements()->saveElement($user);

    return $result;
}

use craftelementsUser;