The title was actually picked up through Xbox Live. When you're playing on PC, Microsoft adds non-Xbox games to your Xbox activity, usually these don't share the same TitleID as the Xbox version though, but in this case it does...
I'll have to check if I can identify if it was played on a different platform. If you earn achievements in it do they even show up on Battle.net? For Blizzard tracking we only have access to their own games, so not sure if we'd be able to see them.
edit: Yeah kinda weird... it just shows up as if you played on Xbox One when checking Microsoft's API. I wonder if this is a bug on their end or if Blizzard plans to use Xbox's achievement system for the game ( seen some posts saying that you can't see the achievements on Battle.net, don't know if this is accurate though).
There is a dedicated menu in the game for challenges and achievements. It doesn't seem to show up anywhere online (also not in the battle.net application) nor in the Call of Duty android app. The achievements don't seem to be tracked anywhere else.