Hi !

I can't remember if she will tell you after you revisit her again who she thinks has the piece or not, but double-check. Sometimes that page reloads (could have been a double-click) and the next one will be initiated without you seeing her take the previous piece.

If she's no longer telling you who might have it, try doing a quest for each of the other possible quest givers to see if they have it.

If you encounter this error again feel free to start a new thread. :)