the NPC phases out for high level toons
Bowmistress Li in Serpent Spine vanishes as does the flight master that brings you to her. This prevents furthering the zone questline.
Yes…phases out for even low level toons.
I am having this same problem.
I am attempting to start questing in Dread Wastes on a lower level character, in order to get the Loremaster achievement, but I can’t start the questline. The breadcrumb quests “The Threat in the South” and “Dread Space” direct you to Bowmaster Li atop the wall between Vale of Eternal Blossoms and Dread Wastes.
I can see the quest giver from a distance, including her yellow question mark, but when you get close Bowmaster Li and the flight master and the meeting stone for the nearby dungeon all phase out of existence. The N’zoth assault is currently up in the Vale for level 120 characters, and I think that is interfering with the phasing for low level toons.
I got on my level 120 draenei paladin, flew to the Vale, talked to Zidormi to go back in time before the N’zoth assault, and flew to the top of the Serpent’s Spine. I have the same problem. As soon as I get close, Bowmaster Li phases out of existence.
Currently, as far as I can tell, I can’t start questing in Dread Wastes. Therefore, I can’t complete my Loremaster achievement.
Still an issue I turned in a bug report ingame I hope they can fix it tomorrow.