I know it's been a while, but we're still experiencing the same problem. The session is somehow not cleared. This code gets executed during logout:  "$self->session(expires => 1);

Then, at login, printing the session variable  say $self->session('username'); sometimes yields the username and the user remains logged in, sometimes it is undefined and the user can log out successfully. I was not able to find a pattern for this, but it doesn't fail only on the server, it also fails on localhost, so there's no connection to that.

Have you investigated whether your script sends the correct Set-Cookie headers upon logout?

If yes, there is a problem with the browser, in that it maybe has old cookies that the program still considers valid.

If no, investigate why the cookie headers are not sent.

I found the error, the request was made using an <a href="" onclick="do_logout()"></a>, which was basically doing 2 actions at once and creating a race condition. Here is the relevant code snippet https://ideone.com/UUeYRw
Thanks for helping!