I have also experienced the problem with the Store Credit mod conflicting with the Group Discount Pricing. It only works if you sort the store credit BEFORE Group Pricing. Sorted AFTER, it generates a negative order total. And the Group Pricing is omitted if you have available store credit that covers the total amount of the order. Then Group Pricing is never considered. I want the store credit to work as the Gift Voucher would (all discounts are calculated first and then the GV or Store Credit is deducted), but it doesn't. Did anyone ever find a fix to this?