Nesting QtQuick.Layouts break the layout properties e.g. alignment

import QtQuick 2.6
import QtQuick.Layouts 1.3
import QtQuick.Window 2.0

Window {
    id: root
    color: "white"
    visible: true

    width: 580
    height: 480

    ColumnLayout {
        anchors {
            margins: 10
            fill: parent
        }

        readonly property var errors: [
            "This is a long message that should wrap when the screen is narrow, and center when the screen is wide.",
            "This should be centered."
        ]

        // Note that blue messages behave properly, and red ones fail.
        // Also, IconMessage is a ColumnLayout, so it's automatically "Layout.fillWidth: true"
        IconMessage {
            iconColor: 'blue'
            messages: parent.errors[1]
        }

        IconMessage {
            iconColor: 'blue'
            messages: parent.errors[0]
        }

        IconMessage {
            enableSpanner: false
            iconColor: 'red'
            messages: parent.errors[1]
        }

        IconMessage {
            enableSpanner: false
            iconColor: 'red'
            messages: parent.errors[0]
        }

        Item {
            id: spacer
            Layout.fillHeight: true
            width: 1
        }
    }
}

import QtQuick 2.6
import QtQuick.Layouts 1.3

// This Item should display a square icon with a wrapping message.
// When the message is short, the row should center horizontally in the column.
// When the message is wider than the column width, the message should wrap.

ColumnLayout {
    id: root
    spacing: 0
    property alias messages: icon_message.text
    property alias iconColor: icon_rect.color
    property alias enableSpanner: spanner.visible

    // When this "spanner" is not visible (or omitted), the layout breaks and nothing wraps or aligns
    Item {
        id: spanner
        Layout.fillWidth: true
        height: 1
    }

    RowLayout {
        Layout.fillWidth: false
        Layout.maximumWidth: root.width
        Layout.alignment: Qt.AlignHCenter

        Rectangle {
            id: icon_rect
            width: 60
            height: 60
            color: 'black'
        }

        Text {
            id: icon_message
            Layout.fillWidth: true
            Layout.fillHeight: true
            Layout.maximumHeight: implicitHeight
            verticalAlignment: Text.AlignVCenter
            wrapMode: Text.Wrap
            maximumLineCount: 2
            elide: Text.ElideRight
            font.pixelSize: 18
        }
    }
}