I've noticed that every few games my KD ratio is displayed incorrectly. It shows as 0 instead of the correct value.
Why is this happening?
Generally this happens if you get disconnected from the game either by connection error or manual ejection, unlike in some other CODS where it just counted whatever your K/D was up until the point you were disconnected. I believe that was by design to counter dash boarding players, personally I don't think its very nice but hey.
If it is just on COD Elite though it is a known bug.