Heiman Temperature & Humidity Sensor

I would like to add two more HS1HT-Z sensors but the inclusion is not successful. I receive “status_request_timeout”. When pairing is initiated (by pressing 3 times the knob), Homey is progressing like with other devices. The green led is flashing for about 30 secs.
When the process repeated (without factory resetting) following message comes: “status.already _added”. I have already tried pairing on many different ways (restart the app; plug out Homey, factory resetting the Heiman sensor, …). There were cases whan I could see new device logs on the Develpoer z-wave page ( As nodes were not responding, all deleted).
I have even excluded one of the existing sensors than restarted the app but I could not reconnect it either. I could read similar symptoms related to a smoke detector but in my case none of my new sensors shown up in the device list so far.
The only thing I have not tried is to remove the app and re install it. In this case I would loose all my related insight data and I would like to avoid it.
Homey Pro: 3.1.0; Heiman App: v1.0.6; external z-wave antenna; 20+ different z-Wave devices.

Any suggestion?