I checked today and the first trial listening on there must be glitched, you press A to join but it says no longer available. I tried joining the one below it and it worked fine.
So this has happened to me quite a bit over the last few weeks with ESO always saying its fixed. Well here is what I do and it does fix it for me for a small period of time, then it eventually goes south and I have to do it all over again.
Disable all your add ons. Then completely close your game. Do the Xbox power button thing where you hold it in for 10 seconds.
After that, fire it all back up. Enable your adds. You should be able to use GF again. If it works for you great. If it doesn't please don't flame.
This is the method that has worked for me last couple of months. Any tickets I have submitted, I'm told its being escalated and I'll be contacted soon. I never get contacted. They always say it's fixed but it really does not seem to be. I just got home and haven't logged on yet. So I don't know if I'm experiencing this again as of today. If I had to bet cash money I'd say it's busted for me too.
ETA: just logged in no GF issues for me atm. Also XboxNA.