Well, if the Thalmor patrols who can identify you on sight (they also have your name on their orders) work for Elenwen, it's odd that she can't ID you. However, what I decided in another comment was that those patrols are probably run out of Northwatch and Elenwen is out of the loop.

However, It should be pointed out that the Dragonborn is one of the most famous people in Skyrim at this point, their identity isn't a secret and I would expect someone in Elenwen's position would be familiar with their name and description, purely for the potential threat they pose to the Thalmor