In Amapi 7 I found these points on the ends of your arch. I tried to fix it so that only quads were used. But then the UV mapping was made worse by by doing that and I don't know enough about Carrara to wrap the right kind of UV info around the arch for the Brick bump function to orientate correctly without pulling facets apart like what's happening in the previous image.

www.youtube.com/user/ShawnDriscollCG