Well, it is what I get when I tick the 'Classic Rewards' box in the fare search environment (I have just repeated the process to be absolutely certain). But you are entirely correct in that it shows the miles for a Flex+ award. So it would be possible that there are no saver awards (which as you say book in 'D') available and it hen defaults to Flex+ awards. Sneeky! It would also explain why there are no upgrades (also 'D' bucket) available. It would explain this entire scenario!