Setting value of session with Ajax not working

For me, Session with ajax working with the following code snippet

add_action('init', 'start_session', 1);
function start_session(){
    if(!session_id()) {
    session_start();
    }
}

// form submition 
add_action( 'wp_ajax_nopriv_form_response', 'form_response' );
add_action( 'wp_ajax_form_response', 'form_response' );

function form_response() {
   $_SESSION['value'] = $_POST['formFiled'];
}

 //Session value
if(isset($_SESSION['value'] ))
{
    echo $_SESSION['value'];
}