When rotating the a device (screen rotation enabled in the global Windows Phone settings) then the Qml interface rotates exactly one time correctly. Successive rotations lead to a distorted screen.

Steps to reproduce:
1.) Start app with phone in portrait mode
2.) Rotate phone -> Qml screen rotates fine.
3.) Rotate back to portrait -> distorted.
4.) Rotate to landscape -> sometimes ok again, often distorted.
5.) Portrait -> distorted, etc.

Qml:
ApplicationWindow {
title: qsTr("Hello World")
width: 640
height: 480
visible: true

Rectangle

}

C++:
QApplication app(argc, argv);
QQmlApplicationEngine engine;
engine.load(QUrl(QStringLiteral("qrc:/main.qml")));