On my first login I set it to stay logged in Forever, and I think that might have caused some issues I had the past week.
My first problem was not being able to mark all messages as read. Following the suggested recommendation I tried to log out. Logging out, unfortunately, was not possible. Clicking on the button to confirm logout just sent me back to the same page with a different token on the URL. Clicking on Stay Logged In had a similar result. Then today I noticed I couldn't post -- the error was displayed after the preview of the post so it was just by chance I scrolled down and saw it.
I solved my problem by clearing all data from this site on the web browser, but I decided to leave this post just in case an admin wants to look into it.
Had a similar problem--may have temporarily been a hiccup in the system that effected only some users but not all, I had to clear my cache twice before it started working.
Fixed when I cleared just the cookies for henthighschool.net from Chrome for me.
About a week ago I've changes session cookie settings. That possible affected all sessions that were created before and were in "remember forever" mode.
I've invalidated cookie settings to force re-login. Now logging-out should work correctly.
Please write in this topic if you still have any session-related issues.