[Crusader]

Cart is also active over here. I had to clear my cache and remove the Kobo cookies stored on my browser. Will need to investigate how coupons are handled now.

Update:
Played around with some of the coupons:
Seems Kobo will automatically apply the highest coupon to the most expensive title in the cart. You then need to add any other coupons you have.

Unlimited use coupons seem to be problematic. I tested 50Dec and was only able to apply it once to a cart containing 3 titles.