The issue was caused when we fixed a bug when the user would manually enter a gift card number at payment, then touching the tip amount would remove the manually entered gift card number. We validated both manual and swiped gift card redeem during our QA cycle and the regression was undetected.
The workaround is to enter a gift card number manually.
How we missed it
The regression occurs when the Magensa mag swipe senses a card number it thinks could be a credit card, when this happens the swipe encrypts the data and our upstream processes decrypt it in the NorthStar services running in the cloud. During our QA cycle we did not use such a card and instead used cards with longer gift card numbers which do not require this extra decryption step. In the future we will be sure to verify both paths and gift card types.
As of 3/3/2016 1:15pm PM PT, we have submitted version 3.3.18 to the App Store with an expedited emergency request for approval. The last time we did this Apple took 8 hours to approve it. We hope that we can release this fix tonight.
Joseph Castillo | CTO | Custom Business Solutions Inc.