Suddenly my Guild Finder (the button we push in the lower righthand corner to display guild window) is greyed out on all my toons. Pressing “J” doesn’t display window either. My guildies can see me in the guild as usual, but I have no access to anything guild related (I’m on Kul Tiras). I’ve reloaded and relogged, and nada. Ideas?
P.S. Looks like several players on Feathermoon had same issue in March.
It’s a known issue. There are posts in Customer Support and Bugs forums.
One on GD this morning, too.
Actually - I just re-read your OP and it sounds different. My Guild & Communities tab can be opened, but the guild isn’t listed. Yours sounds different. 
Have you submitted a ticket?
Yes, I did. Thanks for taking the time to comment. 
Yeah, I have an open ticket, too. I can at least access the roster via /groster. Have you tried that?
I didn’t know about that! Thank you. It does open and display who’s playing, etc. But still no access to guild chat.
Yeah, I have the same issue with no chat, although I can at least open the Guild & Communities tab. It just doesn’t display the guild at all/looks like a guild-less character.
Lemme see if I can find the support thread I was reading yesterday and I’ll link it.
Here’s a blue post on it:
It’s currently affecting a lot of players on Moonguard and Kel’thuzad, seems to be about 50/50 on those two servers.