Deferred properties are not always executed

#include <QtQml>

class DeferredType : public QObject
{
    Q_OBJECT
    Q_PROPERTY(QObject *object MEMBER m_obj)
    Q_PROPERTY(QQmlListProperty<QObject> list READ list)
    Q_CLASSINFO("DeferredPropertyNames", "list,object")
    Q_CLASSINFO("DefaultProperty", "list")

public:
    DeferredType(QObject *parent = nullptr) : QObject(parent) { }

    QQmlListProperty<QObject> list()
    {
        return QQmlListProperty<QObject>(this, m_list);
    }

    void print(const QString &type, const QString &props)
    {
        qDebug().noquote() << type << props;
        qDebug() << "\tlist:" << m_list << "\n\tobj:" << m_obj;
    }

private:
    QObjectList m_list;
    QObject *m_obj = nullptr;
};

static DeferredType* executeDeferred(const QString &qml)
{
    QQmlEngine engine;
    QQmlComponent component(&engine);
    component.setData(qml.toUtf8(), QUrl());
    DeferredType *object = static_cast<DeferredType *>(component.create());
    qmlExecuteDeferred(object);
    return object;
}

static void testDeferredType(const QString &type)
{
    executeDeferred(QString("import QtQml 2.0; import DeferredType 1.0; %1 { }").arg(type))->print(type, "");
    executeDeferred(QString("import QtQml 2.0; import DeferredType 1.0; %1 { QtObject { objectName: 'mylist' } }").arg(type))->print(type, "+ mylist");
    executeDeferred(QString("import QtQml 2.0; import DeferredType 1.0; %1 { object: QtObject { objectName: 'myobject' } }").arg(type))->print(type, "+ myobject");
    executeDeferred(QString("import QtQml 2.0; import DeferredType 1.0; %1 { QtObject { objectName: 'mylist' } object: QtObject { objectName: 'myobject' } }").arg(type))->print(type, "+ mylist + myobject");
}

int main(int argc, char *argv[])
{
    QCoreApplication app(argc, argv);

    qmlRegisterType<DeferredType>("DeferredType", 1, 0, "EmptyDeferredType");
    qmlRegisterType(QUrl("qrc:/DeferredTypeWithList.qml"), "DeferredType", 1, 0, "DeferredTypeWithList");
    qmlRegisterType(QUrl("qrc:/DeferredTypeWithObject.qml"), "DeferredType", 1, 0, "DeferredTypeWithObject");
    qmlRegisterType(QUrl("qrc:/DeferredTypeWithListAndObject.qml"), "DeferredType", 1, 0, "DeferredTypeWithListAndObject");

    testDeferredType("EmptyDeferredType");
    testDeferredType("DeferredTypeWithList");
    testDeferredType("DeferredTypeWithObject");
    testDeferredType("DeferredTypeWithListAndObject");
}

#include "main.moc"

import QtQml 2.0
import DeferredType 1.0

EmptyDeferredType {
    QtObject {
        objectName: "list"
    }
}

import QtQml 2.0
import DeferredType 1.0

EmptyDeferredType {
    object: QtObject {
        objectName: "object"
    }
}

import QtQml 2.0
import DeferredType 1.0

EmptyDeferredType {
    QtObject {
        objectName: "list"
    }
    object: QtObject {
        objectName: "object"
    }
}

EmptyDeferredType 
	list: () 
	obj: QObject(0x0)
EmptyDeferredType + mylist
	list: (QObject(0x949090, name = "mylist")) 
	obj: QObject(0x0)
EmptyDeferredType + myobject
	list: () 
	obj: QObject(0x949680, name = "myobject")
EmptyDeferredType + mylist + myobject
	list: (QObject(0x949f00, name = "mylist")) 
	obj: QObject(0x949d10, name = "myobject")
DeferredTypeWithList 
	list: (QObject(0x94a550, name = "list")) 
	obj: QObject(0x0)
DeferredTypeWithList + mylist
	list: (QObject(0x94ad50, name = "mylist")) 
	obj: QObject(0x0)
DeferredTypeWithList + myobject
	list: () 					<=== !!!
	obj: QObject(0x94b3f0, name = "myobject")
DeferredTypeWithList + mylist + myobject
	list: (QObject(0x94bd40, name = "mylist")) 
	obj: QObject(0x94bb80, name = "myobject")
DeferredTypeWithObject 
	list: () 
	obj: QObject(0x94c0e0, name = "object")
DeferredTypeWithObject + mylist
	list: (QObject(0x94c8d0, name = "mylist")) 
	obj: QObject(0x0)				<=== !!!
DeferredTypeWithObject + myobject
	list: () 
	obj: QObject(0x94d080, name = "myobject")
DeferredTypeWithObject + mylist + myobject
	list: (QObject(0x94d880, name = "mylist")) 
	obj: QObject(0x94d6c0, name = "myobject")
DeferredTypeWithListAndObject 
	list: (QObject(0x94df30, name = "list")) 
	obj: QObject(0x94dd50, name = "object")
DeferredTypeWithListAndObject + mylist
	list: (QObject(0x94e6c0, name = "mylist")) 
	obj: QObject(0x0)				<=== !!!
DeferredTypeWithListAndObject + myobject
	list: () 					<=== !!!
	obj: QObject(0x94ee10, name = "myobject")
DeferredTypeWithListAndObject + mylist + myobject
	list: (QObject(0x94f730, name = "mylist")) 
	obj: QObject(0x94f5b0, name = "myobject")