Session lost after redirect

I need help for this issue:

Code:

function login_validation() {
    $this->load->library('session');
    
    
    $this->session->set_userdata('session_nickname', $this->input->post('nickname', TRUE));
    var_dump($this->session->userdata('session_nickname'));  // PRINTS the nickname OK
    redirect('/main/dashboard');
}

function dashboard() {
    $this->load->library('session');
    var_dump($this->session->userdata('session_nickname'));  // PRINT NOTHING
}

Te issue is I lost all my session vars after the redirect, in function login_validation the value printed is correct but in function dashboard no.

My config file is:

Code:

$config['sess_driver'] = 'database';
$config['sess_cookie_name'] = 'ci_session';
$config['sess_expiration'] = 7200;
$config['sess_save_path'] = 'ci_sessions';
$config['sess_match_ip'] = TRUE;
$config['sess_time_to_update'] = 300;
$config['sess_regenerate_destroy'] = FALSE;

Any Ideas? I'm desperate. Thank you in advance.