QTranslator::load(QLocale(),...) not working

QTranslator::load function with QLocale not working after upgrading to QT5.12.3, it works in QT5.12.0, the sample codes as following:

QTranslator translator;

// look up e.g. :/translations/myapp_de.qm

if (translator.load(QLocale(), QLatin1String("myapp"), QLatin1String("_"), QLatin1String(":/translations"))) app.installTranslator(&translator);