The error was attributed to a processing mistake that occurred between the bank and at least one payment network, according to a person familiar with the matter who asked not to be identified because details of the malfunction aren’t public. Jim Issokson, a spokesman for MasterCard, and Paul Cohen, a spokesman for Visa, didn’t immediately return phone calls and e-mails seeking comment. Apple Pay is part of Chief Executive Officer Tim Cook’s push to expand the company into new businesses while upgrading core products, including the iPhone and iPad.