WebView does not load url

[Mark81]

I'm trying a very simple test application on Raspberri Pi 3, with a Buildroot environment and Qt 5.12.5.

main.cpp

#include <QGuiApplication>
#include <QQmlApplicationEngine>
#include <QtWebView/QtWebView>

int main(int argc, char *argv[])
{
    QCoreApplication::setAttribute(Qt::AA_EnableHighDpiScaling);

    QGuiApplication app(argc, argv);
    QtWebView::initialize();

    QQmlApplicationEngine engine;
    const QUrl url(QStringLiteral("qrc:/main.qml"));
    QObject::connect(&engine, &QQmlApplicationEngine::objectCreated, &app, [url](QObject *obj, const QUrl &objUrl) {
        if (!obj && url == objUrl) QCoreApplication::exit(-1);
    }, Qt::QueuedConnection);
    engine.load(url);

    return app.exec();
}

main.qml

import QtQuick 2.12
import QtQuick.Window 2.12
import QtWebView 1.1

Window {
    visible: true
    width: 640
    height: 480

    WebView {
        url: "http://www.google.it"

        onLoadProgressChanged: console.log(loadProgress)
        onLoadingChanged: console.log(loading)
    }
}

Here the output:

# ./testWeb --no-sandbox
QML debugging is enabled. Only use this in a safe environment.
[0203/081353.795855:WARNING:resource_bundle_qt.cpp(116)] locale_file_path.empty() for locale 
[0203/081353.906904:WARNING:resource_bundle_qt.cpp(116)] locale_file_path.empty() for locale

The screen shows the blank window only.
I don't think the warnings about the locale are critical to load an URL (anyway I'm trying to understand how to fix them).

Any idea?
Thanks in advance

[Mark81]

Well, it was simple enough:

    anchors.fill: parent