I recently was in Asia and attempted to change my return to the U.S. on CX, booked in F class on an AAdvantage award. Although I ultimately secured another flight, it wasn't very easy. Over 80% of the transpac flights I looked at were still showing F4, A4 (I was looking at departures from 1 day to 7 days out), and this was supported by seat maps which indicated a very low number of reserved seats on many of the flights.

Nevertheless, AA was only able to identify one flight as being available, and I took it. Upon boarding, I observed only 2 other pax in the cabin.