Is the so-called "Gateway Mode" still active if you come back from standby?
It seems so.
Going in and out of software (dont have any dsi ware to test though) and putting it on standby for a while still has it on "gateway mode".
Dont have a red gateway card to test yet but when it's in this mode regular 3ds carts dont show up, ds games, flashcards and dsi enhanced games however do.