No, for some reason some games don't report back correctly via Steam API. I know some games are removed from the API (or pulled from Steam Store) for one reason or another but I don't know where to find any list that we could check against to see if that is why. If you know what game is missing you can manually add the game and put the right Steam path in the game's application path, then all the Steam features should work with it. Not ideal, but gives you something to work with in the interim.