at least you are getting one!
It's clear to me that card drops aren't simply randomly staggered. They need you to perform a specific thing, but only after the random counter has deemed appropriate for the card to drop, will your action reward you a card.
I've been creating new games and joining friends (the few I could join, thanks useless 10 minutes rule) from after the store update until a couple hours later, and got nothing. Just now I came back to the PC, saw my group sucked balls still (only level 200ish), dropped it and started a new game and immediately got a card. Now I'm sitting in a room waiting for the counter to fill, to see if the random timer will let me get the other card after killing the level 10 boss.
I can forget the one for joining a friend down the line though, because fuck you Valve and your 10 minutes rule.