Hi guys!
As qdelpeche mentioned, the “None” row is simply due to the prebuilt decks not having been generated just yet. This requires the deck builder (or even just the main menu) to be loaded at least once for the decks to be created and saved so they can be read by the game. After you have opened the menu once, then everything should work without issue, including being able to start a game directly from the arena/level opened in the editor. If you create new prebuilt decks through the editors data table (not in-game), then you will need to follow the same steps and open the deck builder for them to be created or updated.
A side note, you can preset the deck used when playing the game directly from the editor in the arena within the game instance.
As for not being able to play cards… there could be a number of gameplay reasons which may cause this, such as not enough mana to play the card, a card condition may not be met (Which should now give you a popup if this is the case as to why the card wont be played), or the card may not be placed on the right side of the board (Some cards are set to also be placed on the opponents side of the board), but in any case, if you can send a support email to some more details about the issue, such as the card being played, screenshot of the game, etc, then I will be able to help you fix this or see where the issue may be occurring.
Thanks qdelpeche for jumping in on this and giving some direction!