Animated Shader Effect behaves differently with 5.8.0

For some reason, the attached sample code behaves differently in Qt 5.7.1 and Qt 5.8.0. With Qt 5.7.1 a nice "spread animation" (see: https://woboq.com/blog/gpu-drawing-using-shadereffects-in-qtquick/waveoverlay.gif) is shown, whereas with Qt 5.8.0 it is just blinking.

the provided sourcecode is pretty much the same that can be found here: https://woboq.com/blog/gpu-drawing-using-shadereffects-in-qtquick.html