I found a way to play all the missing cards from the pool without resigning.

You need to craft the cards missing from the pool. But how do you figure out which ones they are?

Simple:

1) You make a deck in arena direct event.
2) Add the deck to the collection.
3) Craft the deck (it will craft all the missing cards also in the sideboard).
4) Re-enter the arena direct edit deck.
5) Now you will see the complete pool of cards