BlackBerry10: locking orientation via bar-descriptor.xml doesn't work

if you set
<autoOrients>false</autoOrients>
<aspectRatio>landscape</aspectRatio>

in the bar-descriptor.xml file, you'd expect the app to start in landscape mode even when the phone is held in portrait mode.

Current outcome:
The app is started (and locked) in landscape mode only if the phone is held in landscape orientation before the app is started