It is possible that the custodial parent didn’t understand that the NCP CSS form was needed. People do get confused – the NCP CSS process generates a fair number of posts here on CC with people questioning the logistics of sending the links, etc. Or it is possible that they applied for a waiver, and just found out that it was not granted at one or more schools (it has to be applied for at each school). I know you feel no desire to give your ex the benefit of the doubt. But it is possible that someone (kid, parent) missed an email or misunderstood the process.