QLocale().uiLanguages() returns empty list on Android 6.x

Calling

QLocale().uiLanguages()

doesn't work as expected on Android 6.x where is always return an empty list. The same bug also happens when using the QML version:

Qt.locale().uiLanguages

The main effect is that calling the load method of a QTranslator passing a QLocale() as first argument simply doesn't work, and apps are not translated.

I attach a simple test app reproducing the issue.

Result on x86 Android emulator with android 6.0

Same apk on Android 9.0, works properly.