Sessions in Codeigniter gets changed during page load

I have same kind of issues with 3.1.9. I use file storage for sessions. Session files are created successfully but, when reloading the page it gets destroyed. I had to downgrade to 3.1.8 to make it work again.

I'm facing this issue in 3.1.8 as well , 
on live server sesssion works well but on local pc & Project replica  in subfolder on live doesn't work well, 
old session values are retained even after logout in different controllers.