My main public chatroom is "Warsaw Poland". Sometimes I can't enter it. Even if I manually click in the UI list it still wont load. No matter what I do I can't enter it. Other chatrooms (other cities) work normally. Sometimes this happens just after starting the game. After a game it sometimes goes away. It's rather erratic.
I still often can't join my closest channel while I can join other channels. After a game I'm magically again in my main channel. It's annoying.
I have this too and created an account just to report it. For me it is the "London, UK" channel, but after a game it doesn't change, I still do not automatically join, nor can I manually join.