I have two versions of this problem. The first is when I did a “buy now” via the auction house the player card was showing in my collection but, was not listed when trying to add to my lineup. For this one I was able to change the filter on the left to show all Forwards and that worked. Seems the player position is not working correctly so, they don’t show under the default filter settings.
The second issue was auctions won when bidding. I win the auction, coins deducted, prompted to add card to collection and it isn’t there. Go back to auction house and now card is listed under lost auctions and the coins are gone. Extremely frustrating! Makes the mode unplayable.