Chats not working. Can't join any chats at all.

I've encountered an issue, which I haven't had before.
I can't join any chats whatsoever, I've tried to do /join commands on channels, but nothing.
I've tried to right-click the chat window and reset, I've checked channels, and the only one that shows is /5 (LFG)
After a while, and a few relogs, the /1 and /5 channels showed, but then after a relog, the /1 was gone again.
I have no idea what's causing this issue, and I'd like to see if there's a way to solve it before I download the client again.