I saw that today (Thank you, FT!) and called the DM. Here's the deal. Yes, it is new. It is occasionally working, but it is still in the "running stage", i.e. sometimes they see an UG and it does not go through, sometimes you would see an ug option, and it won't go through for them.

Technically, the classes to look for on EF are:
If you booked the AF ticket on K,B,Y (Coach)-- look for E, and if it is available you can get PV (In theory).
If you booked S,W,A (Premium Voyager), look for O, and if it is available you should be able to book it.

Look for the inventory under the AF flight and not under the DL flight. On the side note, though- Both O and E are also competing with people who book award seats (miles alone). Both do not have stand-by (per DM desk, not even for AF elite pax themselves, though that one I think is incorrect). Both can not be cleared on the same day, and even if it becomes available the day before but you've already checked in (TATL check in on AF is 30 hours prior), you're done...