Have either of your tried retsarting the game, rebooting your console or doing a hard reset (basically full switch off including unplugging the power) and then checking again? The alternative method is to check here on Waypoint: https://www.halowaypoint.com/en-us/games/halo-wars-2/packs/unopened
I have been posting the problem from this thread (which I hadn't seen) in another thread. You can find my post here: https://www.halowaypoint.com/en-us/forums/f0258e8001734968984e8b56990f8daf/topics/blitz-packs-not-added/351a36e2-f2fc-4114-9140-ff1d2fa3fd3a/posts
The link that you provided actually shows my correct card library
but this is not what has shown up in the game for me for the week that surrounded my problem. I can check again today on the XboxOne but I have tried it a bunch already with rebooting it - though not the hard reset. I have "quit" the game and started up again as well.