Verify private/protected property was set from constructor

How can I test the protected property was correctly initialized in constructor?

Code looks as follows:

public class ClassUnderTest
{
    protected List<Update> Updates { get; }

	public ClassUnderTest(string email)
	{
	    Updates = StaticDatabaseContext.Updates.Where(update => update.email.Equals(email)).ToList();
	}
}

Then the test code looks as follows:

[Test]
public void UpdatesAreInitializedCorrectlyInConstructor()
{
    var updatesTable = Isolate.Fake.Instance<Table<Updates>>();
    Isolate.WhenCalled(() => StaticDatabaseContext.Updates).WillReturn(updatesTable);

    var updates = new List<Updates> { update1, update2 };
    Isolate.WhenCalled(() => updatesTable).WillReturnCollectionValuesOf(updates.AsQueryable());

    var target = new ClassUnderTest("user@email.com");

    // throws an error
    Isolate.Verify.NonPublic.Property.WasCalledSet(target, "Updates").WithArgument(new List<Updates> { update1 });
}

My Isolate.Verify throws an error:

Problem here is, that Isolate.Verify.NonPublic can work only with fakes 

1. so either target have to be faked
2. or Updates set property have to be faked (via Isolate.NonPublic.Property.WhenSetCalled)

Regarding 1.

While I am creating new instance of ClassUnderTest in test code, Isolate.Fake.NextInstance does not work.

Regarding 2.

While the Updates property is not static Isolate.NonPublic.Property.WhenSetCalled(typeof(ClassUnderTest), "Updates").IgnoreCall() cannot be used.

Also Isolate.NonPublic.Property.WhenSetCalled(target, "Updates").IgnoreCall() cannot be used, becase target has already been created and Updates has already been set in constructor.

Is there a way how can I verify my property has been initialized correctly in the constructor?