Fibaro FGD212 Dimmer 2 not working any more

Hi guys (and girls if any),
i am a Little confused. I used to use my FGD212 Dimmer 2 with success in my working openhab2. For some reason from one day to the other (without updating openhab) it stopped working. It is shown online in PaperUI, Log Shows ist receiving commands and yet the Lights stay at 100%.
I already tried resetting it, exluding, including… all with no success…
Any ideas where to start?

The official documentation section “when things don’t go as planned”