Turns out they did issue store credit after all for the amount of the promo codes. Just took them an extra day. This was an online purchase and return BTW.
Anyway, enough griping about returns. Sorry for the derail.
I returned $150 in merchandise, mostly paid for with promo codes from past returns, and was only refunded about ten bucks to my credit card.
I'm hoping this doesn't mean I lose the $140 in store credit.