I have had the same problem since the 19th, I have yet to get a response in-game about how to fix this. Guild chat is also gone for me was working one minute, the next it stopped. I have debated reinstalling the game completely but I am hesitant to even believe that this could be fixed by that.
The only responses I have received from my tickets in-game have told me to make sure it was turned on in the chat settings options (under the tab itself) and then they closed the ticket immediately; or the best one was a reply: "Known bug, thank you for reporting this issue"
This is a known issue.
There doesn't seem to be a working solution for this. For some, quitting and re-joining a guild worked (why I don't know).
I had this bug before, too and it just disappeared.
I think there's not much else to do than wait for a fix and spam the official forums like all the others do