Replying to my own post -- I'm now using ITN's advanced mode to look at the details of the flights at issue. I'm consistently shocked to see Y0 B0 H0 K0 M0 L0 S0 V0 N0 O0 across the board on so many flights on so many different days. Does this reflect a post-Sep 11 service cut? (Cut too many flights, and now demand exceeds seat inventory?)

Or a deliberate zero'ing-out of inventory by CX? This might make a certain amount of sense -- helping them sell the more profitable last-minute Business fares rather than the (relatively) cheaper Coach fares.