session data lost after redirect

hi , 
i using CI 3.0.4 and also flexi_auth lib ,
When I login, in login page i set user info in  session by set_userdata  ,
after set session redirect page To other controller but the session data which i set , was be destroyed 

this is my session config 

$config['sess_driver'] = 'files';
$config['sess_cookie_name'] = 'ci_session';
$config['sess_expiration'] = 7200;
$config['sess_save_path'] = sys_get_temp_dir();
$config['sess_match_ip'] = TRUE;
$config['sess_time_to_update'] = 300;
$config['sess_regenerate_destroy'] = FALSE;


And this is my output from print_r($this->session->all_userdata());


Array
(
[__ci_last_regenerate] => 1495024729
)



But When I Set $config['sess_cookie_name'] = '';

I can see my data in session