Shield Route Filtering via group

I have the following lines in my Config/Routes.php:

PHP Code:

$routes->get('/', 'Home::index');

$routes->resource('api/clients', [
    'controller' => 'API\Clients',
    'only' => ['index', 'create'],
    'filter' => 'group:admin,superadmin',
]);
$routes->presenter('clients', [
    'controller' => 'Clients',
    'only' => ['index'],
    'filter' => 'group:admin,superadmin',
]);

service('auth')->routes($routes); 


The public string $defaultGroup = 'user'; in Config/AuthGroups.php for a newly registered user is unchanged. However, when I navigate to http://localhost/clients (with a user in the default group) I can still see and interact with the page just fine. I confirmed the group alias filter is being applied to the route by using php spark filter:check GET /clients. It generated the following:

Code:

+--------+----------+----------------+---------------+
| Method | Route    | Before Filters | After Filters |
+--------+----------+----------------+---------------+
| GET    | /clients | group session  | group toolbar |
+--------+----------+----------------+---------------+

So the filter is being applied, but the arguments of admin,superadmin do nothing to filter a member of the user group. What am I doing wrong?

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