To get Zidormi to appear you have to complete the “Return of the Black Prince” story line starting with “An Unwelcome Advisor” for Ally or “Return of the Black Prince” for Horde up to and completing “Network Diagnostics”.
This requires that you have received the heart of Azeroth, unlocked Nazjatar, and empowered the heart.
Some of the required heart quests can be picked up from the Earthen Guardian in either Borealis or Dazar’alor.
Be sure to have unlocked world quests by doing either “Uniting Kul Tiras” or “Uniting Zandalar” in order to unlock Nazjatar which requires “The Warchief’s Order” or “The Wolf’s Offensive”
If you can pick up the quest:
“A Brother’s Help”. Complete this chain until it ports you back to the heart chamber.
And then, and this is a strange one, you may have to do some or all of the following:
- Log out completely
- Change characters
- Pick up the quest “A Titanic Problem”, fly to Vale of Eternal Blossoms with the quest in your log and abandon it there.
For whatever reason #3 is the step that actually makes her visible for me after everything else has been done. Even with doing everything else the ruined version Vale is still phased until I did that step. Bizarre, I know…
After that be sure to abandon any remaining/follow-on quests from that quest chain and she should be visible.