Automapper not properly mapping child collection

Question

I'm seeing different behavior mapping TypeView -> Type when I map the types directly, vs when that type is used in another type.

In this example I want to map from the View types into the non-View types:

    //db model
    public class TestClass
    {
        public DateTime CreateDate { get; set; }
        public List<ChildClass> ChildClasses { get; set; }
    }
    public class ChildClass
    {
        public long Id { get; set; }
        public DateTime CreateDate { get; set; }
    }

    //view model from client
    public class TestClassView
    {        
public long Id { get; set; }
        public DateTime CreateDate { get; set; }
        public List<ChildClassView> ChildClasses { get; set; }
    }
    public class ChildClassView
    {
        public DateTime CreateDate { get; set; }
    }

In this case I don't want CreateDate to be settable by the view, as it is a generated field. So define my mapping profiles to ignore it on both the parent and child views:

    CreateMap<TestClassView, TestClass>()
        .ForMember(x => x.CreateDate, config => config.Ignore())
        ;
    CreateMap<ChildClassView, ChildClass>()
        .EqualityComparison((m, v) => m.Id == v.Id)
        .ForMember(x => x.CreateDate, config => config.Ignore())
        ;

    //automapper configuration
        services.AddAutoMapper(c =>
        {
            c.AddCollectionMappers();
        },typeof(TestClassProfile).Assembly);

So now I write a unit test to verify that the CreateDate is ignored, but I get different results for the ChildClass.CreateDate when I map directly from ChildClassView -> ChildClass than when I map the TestClassView -> TestClass.

This test passes:

    var target1 = new ChildClass
    {
        CreateDate = new DateTime(2022, 1, 1)
    };
    var source1 = new ChildClassView
    {
        // no create date set
    };
    Mapper.Map(source1, target1);

    //works
    target1.CreateDate.Should().Be(new DateTime(2022, 1, 1));

This does not:

    var target2 = new TestClass
    {
        ChildClasses = new()
        {
            new ChildClass
            {
                Id = 1,
                CreateDate = new DateTime(2022, 1, 1)
            }
        }
    };
    var source2 = new TestClassView
    {
        ChildClasses = new()
        {
            new ChildClassView
            {
                Id = 1,
                // no create date set
            }
        }
    };

    Mapper.Map(source2, target2);

    //doesn't work. CreateDate is DateTime.MinValue.
    target2.ChildClasses.First().CreateDate.Should().Be(new DateTime(2022, 1, 1));

Why does it seem like Automapper is ignoring my config value in the second example? How do I get it to respect the mapping for my child class when mapping the parent class? I tried to explictly state where the mapping for ChildClasses should come from, but got the same result.

I tried making ChildClass as a singular property under TestClass, and that properly mapped. It's only when mapping a collection that it's wrong.

UPDATE: I tried using the answer from this question as suggested in the comments, but i'm still getting the same result. See above where I added the AddCollectionMappers() and the EqualityComparison specification to my child type.