It works, sorta.
Through the app, the discount is applied. However they didn’t bother to conceive of the possibility that the same purchaser could be premier so the app tries to charge extra fees for selecting E+ seating as you go through the purchase flow. So you have to select E- seats and wait until after ticketing to change.
Then, at the last step in the purchase flow, the app crashes. So then you get to try to figure out whether the purchase was completed or not.
Crappy implementation and testing by the app team.