Setting WebEngineView.profile by id has no effect

import QtQuick 2.15
import QtQuick.Window 2.15
import QtWebEngine 1.11
import QtQuick.Controls 2.15
import QtQuick.Layouts 1.15

Window {
    id: root
    width: 960
    height: 960
    visible: true
    title: qsTr("webengineexample")

    Shortcut {
        sequence: StandardKey.Quit
        onActivated: {
            Qt.quit()
        }
    }


    WebEngineProfile {
        id: customprofile
        httpAcceptLanguage: root.httpAcceptLanguage
        httpUserAgent: root.httpUserAgent
        httpCacheType: WebEngineProfile.DiskHttpCache
        cachePath: "/tmp/webengineexample/customprofile/cache"
        persistentStoragePath: "/tmp/webengineexample/customprofile/data"
        persistentCookiesPolicy: WebEngineProfile.ForcePersistentCookies
        storageName: "customprofile"
    }

    WebEngineProfile {
        id: inkognitoProfile
        offTheRecord: true
        httpAcceptLanguage: root.httpAcceptLanguage
        httpUserAgent: root.httpUserAgent
    }

    WebEngineView {
        id: webEngineView
        anchors.fill: parent
        // this fails
        profile : customprofile

        // The following works
//        profile {
//            httpAcceptLanguage: root.httpAcceptLanguage
//            httpUserAgent: root.httpUserAgent
//            httpCacheType: WebEngineProfile.MemoryHttpCache
//            cachePath: "/tmp/webengineexample/customprofile/cache"
//            persistentStoragePath: "/tmp/webengineexample/customprofile/data"
//            persistentCookiesPolicy: WebEngineProfile.ForcePersistentCookies
//            storageName: "customprofile"
//        }

        settings {
            autoLoadImages: true
            dnsPrefetchEnabled: false
        }
        url: "https://youtube.com"
//        url: "https://ping.eu"

        property Menu contextMenu: Menu {
            Repeater {
                model: [
                    WebEngineView.Back,
                    WebEngineView.Forward,
                    WebEngineView.Reload,
                    WebEngineView.SavePage,
                    WebEngineView.Copy,
                    WebEngineView.Paste,
                    WebEngineView.Cut,
                    WebEngineView.CopyLinkToClipboard,
                    WebEngineView.DownloadLinkToDisk
                ]
                MenuItem {
                    text: webEngineView.action(modelData).text
                    enabled: webEngineView.action(modelData).enabled
                    onClicked: webEngineView.action(modelData).trigger()
                    icon.name: webEngineView.action(modelData).iconName
                    display: MenuItem.TextBesideIcon
                    }
                }
        }

        property Menu contextMenu2: Menu {
            Repeater {
                model: [
                    WebEngineView.Back,
                    WebEngineView.Forward,
                    WebEngineView.Reload,
                    WebEngineView.SavePage,
                    WebEngineView.Copy,
                    WebEngineView.Paste,
                    WebEngineView.Cut,
                    WebEngineView.CopyLinkToClipboard,
                    WebEngineView.DownloadLinkToDisk
                ]
                MenuItem {
                    text: webEngineView.action(modelData).text
                    enabled: webEngineView.action(modelData).enabled
                    onClicked: webEngineView.action(modelData).trigger()
                    icon.name: webEngineView.action(modelData).iconName
                    display: MenuItem.TextBesideIcon
                    }
                }
        }

        onContextMenuRequested: function(request) {
            request.accepted = true;
            contextMenu.popup();
        }
    }


    property string httpUserAgent: "Mozilla/5.0 (X11; Linux x86_64; rv:90.0) Gecko/20100101 Firefox/90.0"
    property string httpAcceptLanguage: "en-US"

}