Reported in the EU forums yesterday. I am having the exact same problem. I went back to Pandaria version and the current version neither are triggering Uuna and I tried running all over the gate area according to all the guides and videos where it does trigger.
Can we get a blue post on that?
Iām having the same problem! I am even trying with different characters but yet, Uuna still not triggering her lines.
I am also having the same problem.
Yep, having the same issue. I completed the scenario, and went on to try and complete the world tour starting with the Gate of the Setting Sun, andā¦ nothing. No amount of flying out/in, walking in, jumping in, ground mount, flying mount, or different characters worked. Even had someone doing the whole Uuna secret questline right alongside me, and he couldnāt get it to trigger either. (Yes, I went to Zidormi and had her take me back in time.)
Please help, Blizz? 
Exactly the same issue here. I completed the scenario, have tried Gate of the Setting Sun multiple times (over many days) on different toons, at different levels and stages of expansion progression, in both BFA and pre-BFA phases (after talking with Zidormi.) Even tried some of the seemingly nonsensical forum suggestions, like mounting the flying disk, jumping down from the gate itself, etc. I went through and methodically stood in every pixel of space within the courtyard. (Yay, quarantine. ;)) Submitted a bug report and a ticket, and the Game Master reply says there is no bug, and that the most common issue is failure to complete a prerequisite step. Not sure what I missedā¦ Back to the drawing board, I guess. Will update if I find the solution. 
Same issue here. Super frustrating to dump so much time into this and then its bugged =(
Iām wondering if there is some other condition I donāt meetā¦but what am I missing? Is it a reputation? An exploration? An achievement?
I can summon her and she has all of her items and glows, but I canāt get her to do the world tour at the gate. Iāve tried and no luck. My husband also tried doing it on his account, and he, too, couldnāt get his to work.
Iām so frustrated. I actually had dreams (nightmares?) over this.
Same bug for me. It is so annoying and blizz empolyee are doing nothing to help or fix it. Just saying that you must be missing something. But I have checked and double checked every part. Blizz it is your game and you should make things work as intended. This is a big bug and has been in the game for 2 years without you fixing it.
I posted a ticket 3 days ago. Got an automated reply telling me to go read wowhead and other fansites (even though my original ticket said Iād done that). Marked it as unanswered and typed out the details again. Finally got a response an hour ago:
"ā¦
Iāve had a chance to review your request and I understand that youāre having some trouble with a somewhat secret āquest-lineā in game,
There are no known issues with this feature at present. Iām afraid that as this sequence is considered āsecretā we cannot give you advice or assistance in getting it completed.
ā¦vague comments about if you think this is a bug, please report it ā¦
I would however recommend going back over the guides offered on the fan-sites such as wowhead. https://www.wowhead.com/uuna-storyline-a-dark-place "
So, the official response is āworking as intended,ā and itās all in our collective heads. Except even those wowhead guides have comments from 8.3 about this not working.
I donāt mind something getting bugged - you release content and things sometimes will break. But donāt just pretend nothing is wrong and that itās user error when everyone is saying itās broken. Acknowledge it and say youāre looking into it and you donāt have an ETA. Itās really simple. Itās at least better than denying it and trying to put the blame somehow on players.
Seems to be the default answer. A group of people have been discussing this in the WoW Secrets Discord and one got that exact reply, with the added comment of āsince itās a secret we canāt offer hintsā. Itās bugged, plain and simple.
Uuna is erratic. She reacts whenever she wants, wherever she wants within the Gate area. This is most infuriating, considering this is one of the few activities that help keep us playing and having fun while in the pre-expansion lull.
I got the same thing today.
I am having the same problem. I have used the macro to check progress. I have completed every task in the first part with no issues. In the world tour I have tried both phases of Pandaria and she will not trigger dialogue in Gate of the Setting Sun.
Would be great to see how this is not a bug yet still a problem for so many people.
I also can not get the step 1 World Tour dialogue to trigger at the Gate of the Setting Sun
Hey there, Birbman! (^_^)/)
Specialist Game Master Gobarannie here. Hope youāre doing great!
Good and bad news, Birbman! The bad news is, we did begin to get contacts about this on Tuesday, and based on that our QA team did test this and was able to confirm thereās currently a bug.
Weāre not aware of any way players can manually get around this bug at this time.
The good news is the developers are aware of the bug, and will be working to get it fixed. I canāt give you any kind of an ETA, since I donāt know if itās something really simple, or will be a complex fix, but do know a fix is in the works!
Thanks for reaching out to us about this. Hope your weekend is [legendary]!
PS - Just in case your day needs any brightening, hereās a [Uncommon]-ly good GM joke:
Why canāt gnomes be paladins?
ā¦
Because they canāt reach the light!
Ok, glad they finally acknowledged the bug and that a fix is on the way.
Confirmed still not working. Confirmed im pissed off.
People wanted the Waist of Time this leads toā¦ not the waste of time itās become.
I have been sitting here (Gate of the Setting Sun) for an hour hoping it was a late trigger for Uuna to speak. Confirmed to be a huge let down. For some reason I canāt get Baaāl even when someone else is there with her so I went and farmed for her for 2 weeks on 4 characters just to be stopped here. 
Same issue here, hope they get it fixed soon
the time i have wasted ā¦ and i cant even get baaāl ā¦ just got to this gate only to see this messā¦