Ahhh that sucks. I would presume your Online CGSM account has been updated with status regarding that.
Honestly, if they're looking for other admitted students to apply for member, I think it might be worth a shot to write to CGSM or Georgetown and reconsider your membership application/essay. It couldn't hurt. If they can give you feedback, perhaps they'll let you re-write your membership essay and consider affording you another shot at membership.
It still won't result in the fellowship, unfortunately, but at least you'd get membership and get to attend OP.