If I open my browser in incognito mode, go to the GoDaddy site, change the currency at the bottom of their site to USD, then the promo code is applied. But I didn't try to go ahead and buy the domain.
Perhaps now GoDaddy requires that the country of issue of the card matches the country of the promo code. Or maybe, as you said, it doesn't work anymore at the moment.
Here are the codes that I know. Maybe someone wants to check it out:
GDD99com1 - USA
ILDOMILS1 - Israel
JODOMUSD1 - United Kingdom
EGDOMEGP1 - for some European country where the currency is Euro, e.g. Germany