I have found the same thing to be true in Asia. I have BF award tickets to CNS via NRT, but am waitlisted for the NRT-GUM, GUM-NRT segments. An award search at CO.com (searching NRT-GUM) shows std BF available for the NRT-GUM flight, but it comes out of "F", and my award is "E" - so they won't process the waitlist upgrade.