session variable desappearing and reappearing randomly

Hi guys, I recently discovered a strange behavior in my app Session, I got a session variable called 'operator' (which is an array that contains some key => value data) that desappear and reappear randomly, but not usually, just sometime!!!! which make no sense.

I made a '/test' route and did a dd(Session::all()); in it just to check the session content, and refreshing many times to see if this variable is really desappearing, and reappearing, and YES! it is!, but, how!, how a variable can do that!!!

knowing that in my app I'm making a long polling ajax request to get updated the UI, but I'm not playing with this variable, (Note that I'm using the session_write_close();)