@philipaarseth - happy to help!
That was a lot of explanation around what goes on behind the scenes but, if you’re using the built-in methods, then you don’t need to do anything extra. I wanted to point out a few other ways of logging in that might be causing the issue. The WP link is just some extra general troubleshooting steps that might be helpful in a PHP environment.
The Quickstart needs an update but what’s there should work out of the box and handle state behind the scenes. If not, which it sounds like it is not in your case, then the questions I asked above should direct you to the right place to debug.