How come PassthroughSubject isn't publishing?

I want a "controller" or "viewmodel" object to be apprised of changes to an object in the data model. So I've set up a Combine publisher in the data-model object, which publishes whenever one of its member values changes:

import Foundationimport Combineclass User : Codable, Equatable, ObservableObject{    var ID: String = ""    {        didSet {            changePublisher.send(self)        }    }    var pw: String = ""    {        didSet {            changePublisher.send(self)        }    }    var username:  String = ""    {        didSet {            changePublisher.send(self)        }    }    var firstName: String = ""    {        didSet {            changePublisher.send(self)        }    }    var lastName: String = ""    {        didSet {            changePublisher.send(self)        }    }    var validated: Bool = false    {        didSet {            print("Publishing validated change.")            changePublisher.send(self)        }    }    let changePublisher = PassthroughSubject<User, Never>()...}

And here's the object that wants to know about changes to the above User. It gets the User passed into it as a member of the model:

class UserManager : ObservableObject{    var model: CentralModel    var userChangePipeline: [AnyCancellable] = []    init(withModel: CentralModel)    {        model = withModel        model.user.changePublisher.sink(receiveValue: { changedUser in            print("Changed-user validation: \(changedUser.validated)"})        .store(in: &userChangePipeline)    }    ...}

The User object is printing the "publishing validated change" message when I alter that value, proving that the didSet methods are called. But the subscriber's sink is never called. Note that I am saving the subscription.

Compounding this problem is that breakpoints are broken in Xcode 15.2.

I also tried changing the User to publish a string instead of itself, but the subscriber still doesn't receive any publication.