Fusion Qt Quick Controls style no longer honors palette/font settings from qtquickcontrols2.conf

System information: Qt 5.12.0 RC, Kubuntu 18.04 x86-64

Problem

Under Qt 5.12.0 RC on Kubuntu 18.04, it appears that font and palette customizations made to the Fusion style via :/qtquickcontrols2.conf are no longer honored; instead, the font and palette set in KDE system settings are used.

Under Qt 5.11.2, it was possible to modify Fusion's font and palette from :/qtquickcontrols2.conf.

Workaround

Font and palette customizations made using QGuiApplication::setFont and QGuiApplication::setPalette are still honored.

Demo

The attached project demonstrates the above issue and the workaround on KDE; I'm not sure what happens on Windows or macOS. The project specifies bright red text on a dark gray background. On Qt 5.11.2, it renders as follows:

On Qt 5.12.0 RC:

On Qt 5.12.0 RC, with font and palette customizations moved to main before QQmlApplicationEngine initialization: