Originally Posted by
Travellin_man
With respect to the 14 day / 21 day window, there was a promotion over Christmas which lengthened the upgrade window to 21 days. It is over now.
Thanks, I must have missed that promo, and it wasn't listed on the website yesterday when I was looking.
That explains OP's 21 days, provided the flight was within the window (although based on the timing of the post, I'm not sure about that), but the question around why OP thought N space = upgrade remains open.