Steam Private Games - DLC

[Jesus]

When you mark a game as Private, it blocks it from your friends seeing it at all. BUT on the store page, you can still see if a friend owns one of the DLC's for said game.
At least this is relevant for Call of Duty. - As the "DLC"'s are just the different games, because it's all in one Hub now.
And still shows the game in your Recent Activity on your profile page. I feel like if something is Private, is shouldn't show up there either.

[Seiren]

It seems they were unable to acknowledge or address this before the holiday. Now that it's over, maybe they can finally do something about private games/purchases showing in the activity feed. The DLC thing seems like a pretty big oversight as well.

[cSg|mc-Hotsauce]

The main issue with the new CoD titles is how Activision set up their Call of Duty® HQ set of games. They are both full games but also DLC for the HQ which will make things extra difficult for Valve to sort out. Same goes for the Master Chief Collection.