Multiple people reporting the issue (and that thread also links to an earlier thread about it). Multiple people having problems with it. Some saying “she’s very picky about the exact spot to trigger” and listing a spot (but none of them have worked for me personally). Others suggesting a ridiculous number of solutions - none of which worked for me personally. Tons of comments having the same issue (never working with respect to those suggestions).
The most likely problem is there’s some conflicting status set that has an effect on a subset of players such as she won’t trigger if the world quest for the big bug is up, regardless of which timeline you’re in (this is absolutely not the case as I’ve tried it without the world quest being up, but just the type of potential bug). This seems most likely.
Another possibility is there is some bit of information that the guides and secrets are missing (such as a time of day or day of the week it must be completed on). This seems unlikely as there doesn’t seem to be any evidence supporting the need for this, or the presence of such a condition. Likewise, referring us to keep re-reading the wowhead guide (and/or other fansites), which doesn’t mention any such condition, would seem contrary to that.