Once you kill her on a map, that instance no longer spawns her until the game has a patch. This needs to get fixed. It's been bugged since 2017!
Have you used /bug ingame to report this? Because only then the devs will a) see this (they rarely take something from the forum and make a bug themselves), b) know exactly in which instance you were and c) know the exact time you were in this instance.
You won't get a reply for a /bug ticket, but it will be placed for the devs.
Was I able to help you or give you a hint? Click on Helpful and/or Thumbs up, I would appreciate it alot!
When you encounter a bug ingame, at first you should file a ticket via the ingame command /bug, as only this way the devs will know exactly where you were, when the bug happened.
It's been reported by several people in the past before.