Not true. Last fall I was flying PEK-SFO on a W fare, used miles and cash to request an upgrade. Day before flight it still had not cleared and I decided I wanted the extra PQM's, PQD's and PQS's so I bought up to a Z fare. Lo and behold the next morning, day of flight, suddenly the upgrade cleared even though I was already in the J cabin. And no, it was not an upgrade to GF, I looked closely. It took a call to get my miles and money back.