I have a Core Data model which has three entities: A, B, and C. A has a one-to-many relationship with B, and B has a many-to-many relationship with C. The delete rule for A
I'm certainly no Core Data expert, but reading the documentation on the various delete rule options, it seems to me that you want the B -> C relationship to be Nullify, rather than No Action. Perhaps the Bs aren't going away because the Cs are still holding references to them?