unbuffered_row() not working - returning null

I'm having trouble with the unbuffered_row() function which doesn't seem to be working at all in CI_VERSION = 3.0.6

In this snippet, the die() never triggers (even though there are definitely results)

PHP Code:

    $sql = "SELECT * FROM some_table";
    $query = $this->db->query($sql);
    while ($row = $query->unbuffered_row()) {
        die('here');
    } 


In this example, the var_dump returns NULL

PHP Code:

    $sql = "SELECT * FROM some_table";
    $query = $this->db->query($sql);
    var_dump($query->unbuffered_row()); 


I've followed the documentation, brief as it is on the subject. Is this a bug in the framework or am I missing something obvious?