Did you make sure you're able to see images? On the top-left, click on "show images". That should let you view the code. Worked for me, at least.
Yeah, tried that, refreshing the image, opening the image in a new tab, etc. Occasionally it'll show up as a small image with the word "coupon" on it, otherwise it remains blank or shows up as a broken image.
I'm probably gonna buy the TCG game when it comes out on VC so I guess I'll get a code by then anyway. Was looking forward to playing it today though :/