Automatic CiviDiscount fails on Event wait list confirmation

We have a site where members login to register for events. Using the CiviDiscount extension, they get an automatic Members discount on the event. This workflow is working as expected.

However, we are also using the waitlist function. When a space becomes available and a member is invited to confirm their registration for the available space, the CiviDiscount module doesn't work and they are presented with the standard rate.

If you take the participant parameter out of the url, the correct price populates. However, that parameter is required so that the participatnt record updates and they come off the waitlist.