Create Conic slope

hi all,

im traying to create conic slopes with the dedicated tool in model detailing. its omposible for me make the slope have the slope that I want. I tried changing the slope format in civil formatting but is completely impossible.

some one had the same problem or an idea what is happening?

and testing the tool in a flat terrain I noticed that the angle between the two lines afect how the cone look. if the angle is less that 90º the result is sharpen and if its more that 90º the result is blunt.

only made the expected result is the angle is 90º

thanks in advance