That means in a model which is moved the bounding box is used for collision detection regardless if POLYGON is set? Well, I read in the manual that I should not do what I'm doing, but I did not get why. Now got it.
But to be honest, I don't like your answer, because it shows me that it is my personal issue and I can't blame anyone else ;-)

Thanks for help - it kept me awake longer than planned, but already found a feasible work around to get what I need.