CI 3.1.1 Session not kept

HI 

I had updated to CI 3.1.1 and i had a problem with session not being kept from 2 urls. If i rollback to codeigniter 3.1.0 works ok.

is there any info on session for the upgrade?
 

PHP Code:

class Test extends CI_Controller {
 

 
public function index(){
  
$this->session->set_userdata('key',"val1");
var_dump($this->session->userdata);

echo "hi";
 

}
public function p(){
var_dump($this->session->userdata);
}

} 


Thanks