I have a second app which is already live on the App Store. I pushed an update to this app, and it was approved and is Pending Developer Release.
I generated a promo code, and redeemed it. It worked fine.
So, maybe the Pending Developer Release -> Promo Code method for giving media access to your prerelease 1.0 builds no longer works.
Apple: Please document this!
Topic:
App Store Distribution & Marketing
SubTopic:
General