HI Gunter,

As I said, I tried your file in Moi version 3 and the boolean works as expected.
I have version 3 and 4 installed on my system.

Best regards

Hi Gunter

part of your issues are the profile you are sweeping is folding on itself in the centre at the bottom
Then when you boolean out the band it self destructs







If you change your sweep profile so does a clean sweep it will work
I have done you an alternative sweep profile to aid in setting the stone

cheers
shayne