Fibaro FGFS101 Flood with ghost sensor

using above sensor, and the new Zwave-JS integration and add-on, I have it successfully setup and tested for functionality.
However, upon install a _sensor_basic showed up, briefly in regular font, after which it greyed out, and now is Unavailable (Niet beschikbaar). Even after waking up, triggering the tamper and flood sensors, beeping al out, this remains grey.

Would anyone know what this sensor is supposed to indicate?

Very similar behaviour here:

Capture d’écran 2021-02-07 095106

Triggering the alarm with actual water does not do anything in HA.

I have two Fibaro flood sensors and the one with zwave+ and firmware 3.2 have the same issue as you describe, binary sensor is missing and nothing is reported when triggering the flood sensor. The older one with firmware 23.23 is working as expected and have more entities enabled by default as seen in screenshot below.

suddenly this ghost sensor had become alive, and turned ‘0’.

still not clear what it does or indicates.