So I leveled a priest to 110 about 2 weeks ago. At that point, he was at least friendly with Court of Farondis, Dreamweavers, Highmountain Tribe and Valarjar. No rep with Nightfallen, even now I'm at 50/3000 neutral. As soon as he turned 110, World Quests showed up on the map (only 1 or 2 in Suramar) and I was able to do them normally, including Emissary Quests.
I leveled another priest to 110 yesterday, he was still neutral with Valarjar and hadn't met any Nightfallen. When he turned 110, a quest popped up immediately: http://www.wowhead.com/quest=43341 (it's called "Uniting the Isles" for me, everything else is the same). I got him to friendly with Valarjar since, but the quest still says I have to get friendly with the Nightfallen.
So my questions are: Can anyone confirm this? Where's the bug here? Should priest #1 have gotten the quest or should the Nightfallen rep requirement not be there? Or am I completely missing something?
I found a few threads about this quest from months ago (abandoning it and not being able to get it again etc.), so I assume it hasn't been added in between.
I guess the TL;DR is: If this is a bug and it doesn't get fixed before release, make sure to get to friendly with the 4 factions before reaching 110 (which really isn't hard, just complete 2-3 chapters in every zone).