I sadly am ecountering the exact same issue as you and others have. I tried with several alts, I switched warmode off, flew in and dismounted, walked around and waited for over an hour, but nothing I tried would trigger her dialogue.
I submitted a ticket, but got a generic unhelpful reply telling me to check wowhead for quest help … I also reported it as a bug, so hope that at least someone will have it look at.
How can she not see that Gate … It’s MASSIVE.
It’s probably got to do with with how the new version of Vale messed up with both zones’ IDs in the DB, and they don’t match the xyz:zone parameter for Uuna’s trigger. Extremely annoying that they haven’t fixed it yet, as the action required for fixing it is a few minutes tops.
Reported the bug - to no avail, obviously. Put in a ticket - got the usual generic copypaste response telling you to consult wowhead.
They spent so much time to create this entire riddle chain and now don’t care that it’s been bugged for weeks. Wtf?
been running around there for several hours today, is it worth even bothering now? I submitted a bug report but not hopeful 
Guys to keep you updated, today a GM contacted me to confirm Uuna is bugged. Here is the message :
" We are aware of this problem, the problem with her bugging at the Gate of the Setting Sun is something our bug team know about but sadly at the moment there’s no work around for this. They’re working on fixing it but I must ask you to be patient whilst they do. This can take a bit of time but they’ll fix it as soon as they’re able."
Thanks for the info :). now at least we can all stop running around like idiots for nothing
Hey,
We have received several reports that Unna appears to be bugging out, this is something that we’ve reported on for investigation, but sadly there is no workaround at the moment.
Apologies for the inconvenience in the meantime.
its not that uuna is bugging out but she pops no dialogue like she should be
i posted this on my monk (chopsick) but ofcourse im doing it on my main jumici, and yes i talked to zidormi and no theres no dialogue popping up no matter what i do
I can confirm its still bugged - tryed again today starting the world tour in the Vale, also in both times…
Hope they fix this soon…!!
Same problem too.
Tried with low level characters to avoid 8.3 version of Vale, but didn’t work 
Same here. It would seem that with the update to the Vale, the background quest prompt has become deactivated for Uuna.
Not only do I want Uuna and Baa’l, I want to start Waist of Time sequence.
Hi,
I can confirm it still works! Did it just now.
I tried all day to get Uuna to talk, but nothing.
For hours I ran like a lunatic around with her at the gate of the setting sun, but still nothing.
Tried it on various alts: a lvl 110 alt, even a 120 horde alt etc., but still nothing.
But then I tried it on a low level 102 and once I summoned her, she started the dialog right away!
I don’t know if it was the low level char or maybe I was there at the right time in the later afternoon, because maybe - just maybe it has something to do with the nearing Night - because Gate of the setting sun… who knows!
Wish I’d seen this post before I spend all morning doing the quest line. Hopefully it gets fixed soon
Testing this for 2 hours 40 minutes over 3 days of running around.
Confirmed blizzards GMs know about it after twice being fobbed off. Really glad they are working on a fix… but still not working after 2 weeks of (personal) reporting. Please fix blizz
This just proves they’re currently fixing it, I like to think. Sadly, I don’t have too many +100 lvl alts and I’m not gonna make one only for that, as anyone would understand… Let’s keep waiting and perhaps it will be available in all characters 
Just attempted this on a lvl 101 Alt and it still didn’t pop
We have the same issue in Rusaia here, although several people posted that they were able to get her to start talking after hours of running around the spot. One guy posted that he was able to do so on 2 characters by running from the rare scorpion spawn straight to the big pandaren near the gate, although I tried that myself and it didn’t work. Anyway, our customer support didn’t even bother to answer the question on the forums, had to find this thread instead. GL everyone.
Still not working…
I have the same issue. Stuck with tour at Gate of the Setting Sun
Having this problem as well in Vale before Invasion.
Will try during Invasion later but that shouldn’t work….
And it didn’t