Soft hyphens are broken

It seems soft hypens are broken (see attached image and code).

QTBUG-44234 suggests to set QT_HARFBUZZ=old which seems to work (graphic #2) unless you call QQuickStyle::setStyle("whatever"). It does not matter if the style really exists or not: Hyphens will be displayed but can be outside of the box, and will be rendered as spaces otherwise (graphic #1).

Not changing QT_HARFBUZZ and not calling QQuickStyle::setStyle() will result in a text without any hyphens (graphic #3).

Just calling QQuickStyle::setStyle() seems to override whatever is set by QT_HARFBUZZ (graphic #4).