Challenge statistics do not seem accurate on COD:MW

Yesterday, a player climbed to the top spot of the 250Kills challenge with over 2000 registered kills, but on his profile, I see in his match details about 200 kills since January 1st. Is this a bug in the challenge or in the detailed match view? It’s just to know, it doesn’t matter if I lose this challenge but there might be a bug somewhere so I prefer to report it :wink:

Have a nice day