QML items are not rendered
<p>Interesting problem with QML. When I create a default Qt Quick application and run it, I get a black screen. Window and other items are not rendered at all. But when I minimize it and return it to previous state again, then items are rendered. So does anyone know about this kind of problem?
<a href="https://i.stack.imgur.com/QzBLm.png" rel="nofollow noreferrer">Before minimizing</a>
<a href="https://i.stack.imgur.com/Rd2ll.png" rel="nofollow noreferrer">After minimizing</a></p>
<p>In a very similar case (for another user), the window was being created, but none of the items were being rendered. In this case the window was completely blank (white) instead of black.
The system was a Windows 10 with Qt 5.15. This issue was not appearing on non-Windows system.<br />
(The solution was related to OpenGL. See details below.)</p>
<pre><code>import QtQuick 2.5
import QtQuick.Window 2.2

Window {
    visible: true
    width: 500
    height: 500

    Rectangle {
        id: test
        width: 300
        height: 200
        color: &quot;red&quot;
        border.color: &quot;black&quot;
        border.width: 4
    }
    
    Rectangle {
        width: test.width / 2
        height: test.height / 2
        color: &quot;red&quot;
        border.color: &quot;black&quot;
        border.width: 4
        anchors.centerIn: parent
    
        Rectangle {
            width: parent.width / 2
            height: parent.height / 2
            radius: width * 0.5
            //x: 200
            //y: 200
            color: &quot;green&quot;
            border.color: &quot;darkgreen&quot;
            border.width: 4
            anchors.left: parent.left
            anchors.bottom: parent.bottom
        }
    }
}
</code></pre>