Guild chat not visible
Make sure the individual Guild Names did not become unticked in the drop-down menu of Guild Chat in your Chat tabs.
If you continue to have issue, you can contact the CS Team via the ‘Support’ link above/below.
Good luck.
Make sure your status isn’t set to invisible, that disables Guild Chat, at least it does for me.
you can’t fix stupid
I have had the same problem for a few days now too.