Coupons by product / item don't seem to work on the 4.2 and 4.3 releases

When setting up a coupon or discount tied to a specific product, make sure you fill in values for these fields:

Min Order
Max Order
Max Uses

Don't just leave them at '0' - put positive numbers in there, and suddenly it works.  I don't know why it's coded this way, but that's what you need to do.