Okay, Chrome and Edge browser are working fine. I am staying logged in, so it seems to only be an issue with Firefox. I have not experienced this issue with any other site.

I have cleared all site data and cookies for all sites via Firefox's "Clear browsing data" function and that does not help at all. As far as what is happening, I'm launching Firefox, and coming to the Org via a Favorites/bookmark. The forum page loads as if I am not logged in to an account. I'm entering my User ID and password ("Remember Me" is checked by default but I've tried unchecking and then re-checking that box). The Org reloads with my account. I can browse around the Org forums as normal. When I'm done, I close down Firefox. Next time I launch Firefox and come here, I get the general forum page as if I'm not logged in.