I’ve noticed that if I go directly to the forums and try to log in, I get “forum user not found”. If I first log into the main plex.tv site, then log into the forums, it works. This happens on various browsers and operating systems.
You’re always logging in with same account? If you are part of a Plex Home, do you have the web app maybe signed into a managed user in another tab or window?
Always same account. I’m not signing in from the machine running Plex. Today, for example, it was on a separate Windows 10 machine via Chrome (which is where I’m replying to you from).