QTextToSpeech::synthesize under window does not get data

When I do call under Windows the function QTextToSpeech::synthesize thene

• The stateChanged(QTextToSpeech::State state) is called correctly with QTextToSpeech::Synthesizing)
• The functor is called just once with the bytes empty.
• The  stateChanged(QTextToSpeech::State state)  is never called with ready.

I have used the functionality with a dev version when you still had the "synthesized event" and the synthesized event was called many times and then the stateChanged with ready.

Now I'm trying to use the release version 6.6.0 with the new version of the API (compliment more clean solution!) but I cannot get any synthesized speech. 
I have tried both version of the synthetize (with a lambda and with a call to a a function) but there are no differences.

I do attach a printscreen with a stop and debug data just after the first call to the functor.

Currently I have no idea how I can help further.