Okay guys I was having the same issue for days, it was very frustrating. I literally just solved it, I know it sounds like it shouldn’t have anything to do with it but right when I finished the allied races questline for the Vulpera, Baine is in her place but when you finish the Vulpera allied races questline you will turn that quest in to Baine, you will then get the achievement for the Vulpera. Then just run out of orgirmmar and back on, when you get back in Sylvanas will be where she is supposed to be and you can turn in the cycle of hatred quest. Hope this helps!
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