Hi Pascal, it happens with both, single surfaces or breps. I’ve found that if i just try to close the dialog instead of pressing the End button, it hangs too for a while. The mesh i’m testing with is the compressor mesh linked by @wim in this thread. If you import it into below file using “Map obj Y to Z”, you might have something to test.
It seems that the displayed colors for the points are wrong as well, i’ll include a screenshot with the values i used.
Test.zip (1.0 MB)
c.