Laravel 5.2 session not persisting

Lately I've been working on a project in Laravel 5.2 and now I'm having problems with sessions not persisting. I've read most of the questions already asked regarding this but everyone has the same answer that I have already tried - applying web middleware.

I've read that there was a new L5.2 update where the web middleware group is already applied by default. I checked my routes with php artisan route:list and I can see that every route has only 1 web middleware applied.

I'm creating session with $request->session()->put('key', 'value') but as soon as I comment that line the session is nowhere to be seen anymore.