This just occurred to me. I just got rejected for a secondary I didn't complete (didn't finish, so didn't withdraw my app) and it made me think of what Dr. Armstrong said about completing the post-interview survey.
Did all of you who were stuck in "limbo" complete your post-interview feedback survey? Dr. Armstrong said that was the only way our applications would go to committee to make a decision. Perhaps if that wasn't done, you weren't included in the original decisions that were sent out (i.e. accept/WL/reject), and they sent a later set to people who didn't do the survey. Not trying to accuse anyone of anything here, just trying to consider reasons this whole thing could be so messed up.
Either way, best of luck to all of you! As others have said, the fact that you even interviewed at Duke means that you're well on your way to a successful career in medicine.
I completed the survey as soon as it became available in the portal.