My listings where I am the only one selling on that ASIN and do not have the buy box has the yellow bar that says "see all buying option" even though I'm the only one selling the item. Its in the same area where it says "add to cart" when you have the buy box, but since I don't have the buy box customers have to click that to get to the option to add to cart. I know it makes no sense since there are no others selling on the listing, I guess it does that by default when you don't have the buy box.
I just added a item that's that's the same item but different character as the one I have the buy box on and used the copy to another product option under actions and I got the buy box on that one right away, even know I haven't sold any of them yet. All in the same category. Doesn't seem to be any rhyme or reason to the way they award the buy box that makes sense.
Thanks for your response.