the most basic wordpress user query […] is displaying that it has
not found any users
You’re passing an empty array of query arguments and there’s an explicit check for that in the WP_User_Query
constructor:
/**
* PHP5 constructor.
*
* @since 3.1.0
*
* @param null|string|array $query Optional. The query variables.
*/
public function __construct( $query = null ) {
if ( ! empty( $query ) ) {
$this->prepare_query( $query );
$this->query();
}
}
so that would explain why you get no results in your basic example.