Tried everything, in vane. Also suspected a conflict with my Rapoo wireless mouse that obviously failed after a while when running Domoticsz.
with and without using the USB stick in a powered USB hub.
Re-installed everything again, no result.
It cost me a too much time and frustration I give up and ...

thanks guy's,
Did the factory reset, as well as re-install Domoticz, same result.
Domoticz do not allow me to delete all the hardware lines.
Starting alll over with the Z-stick in a powered hub did have some result, this resulted into the stick as COM8, and a new hardware line.
This new line ...

Have a Z-stick Gen 5 ZW090 (not the +) hooked up on my windows notebook USB port.
Windows settings "bluetooth and other devices" shows this as: " USB serial device (COM 3)

Domoticz Setup Hardware button shows screen with nine etries:

7 times: OpenZWave USB Version: 1.6.1911.gc6a420ef.dirty Setup ...