Originally Posted by Fishbait
Most likely this is because F is sold out. Elite Y upgrades come from A inventory, so if there is A available, it's yours. Always check for flights with availability in the F cabin before purchasing full-Y to be sure you get up front.
Robin
I was just pointing out that buying a Y today doesn't mean that you'll automatically get F, even as an elite. You have to make sure the golden U is there.