"The Back Side of Deck/Set Has Not Been Proofed" Error Message

Please note that you must upload and proof a deck back image for every card deck and component set, even if each card/component will have its own unique back image.  The deck back/component set back image will be visible under your the components list on your game's Shop page, so you'll want to use an image that is presentable even if it's not printed on any of your cards/components.

Here's an example of how the image will appear on the Shop page.  The image is displayed as a thumbnail, but is enlarged when the cursor is hovered over it.