Pro Sites coupon not applying to PayPal total, not showing up as a use

Hello good WPMUdev-ers-

I'm having an issue with the coupons on Pro Sites. The coupon, when applied, shows the discount on the level panes (screenshot attached), but when one is selected and I go to PayPal (using Express), the discount has not been applied to the total. Furthermore, even if I go through with that sale, the coupon itself has not been logged as having been used. It's still at "0". Recurring payments are turned off on Pro Sites.

We do intend to go to PP Payments Pro at some point, but not yet, and I don't think that's it. The discount never makes the transition to PayPal.

Try it! The coupon is TESTING and the discount is an indefinite 99% off any level. Link. I'll nuke the test accounts later.

Thanks for your consideration of help.