So I got brand new, shiny 3D finder from https://www.sorotec.de/shop/3D-Finde...nsor-6411.html
Connected it, spent some time getting it perfectly calibrated. A few fun hours in a workshop. I followed instructions, set all the parameters. So far so good.
Then I triggered "Calibrate Z" under Calibrate Probe Z Height - it worked just as expected. In 3D finder manual, it recommended to run it several times - so without doing or touching anything, I triggered "Calibrate Z" again. It worked as expected as well.
But after that it followed by a full speed negative Z plunge of about 10-15 mm straight into the ball bearing.
As a result, I no longer have a 3D finder.
I understand that somehow I should have known that triggering auto calibration will result in this crash, I just don't what I have missed.