Tex, Michael, and I are all in the same single guild with this happening. None of the other guilds we're in have this issue. I see the same as Michael as well.
I (and I think they both have too) have closed and relaunched the client. I've gone invisible, then available again. I also tried just going to character select then logging back on (same character). Same issue every time.
None of the other guild functions we've tried seem to be having any issues. And no other chats outside of guild chats are having any issues.