Not sure if anyone else has had this problem before, but I think there's a bug relating to upped cards.
When I upgrade cards, and put them in decks, and use those codes for later use, the deck is not full because those cards aren't there
Not too sure, but it may looks like the game has eaten my electrum as well (9000 in this case)
Before anyone asks, yes I do wait for the game to say it's saving, and confirmed
If it helps, my arena deck is saved as well
EDIT***
In my card pool, there are 12 of that card, but none are upped (I bought the cards from the bazzar to upgrade them, and they are there in their unupped form the next time I login)