Manual testing - clip-planes-qml displays a black screen upon start

The manual test clip-planes-qml will only display a black screen when running. These warnings are outputted:

• Unknown uniform type or value: QVariant(QString, "black") Please check your QParameters
• Unknown uniform type or value: QVariant(QString, "blue") Please check your QParameters
• Unknown uniform type or value: QVariant(QString, "white") Please check your QParameters

The black screen issue can be fixed by adding this line in main.cpp:

qputenv("QT3D_RENDERER", "opengl");

This does not resolve the warnings shown above.