I found a workaround for the action upon motion detection.
When I added the presence sensors as Thing in Openhab, each of them had a “power” channel that apparently toggles if the sensor actually fires. So I configured an Item and then turned it on because by default it was turned off. Now the sensor control in Phoscon works almost as expected.
There is something like that documented for deCONZ (Motion sensor pro (MOSZB-140) - deCONZ REST-API ) but what I found looking like it was “false” und greyed out
What still does not work is to resume to the last state before the sensor fired. In the sensor control, one action is called “turn on group with last settings” which i reckon could mean what I itend to achieve. Unfortunately, already in September some other user was ignored requesting to be shed a light on what the actions actually mean and I second his hint on thin documentation regarding that matter.