I don’t quite know what the error message means? My guidelines are attached to both profiles.
Hello! The meaning of the message, in this case, is that the guide curve is not aligned to the cross-section. When applying the guided loft tool, please select the cross-sections first, then the guide curves.
I am not sure by the screenshot, have you selected the back face of the cone before the guide curve?
I did yes, but it still didn’t work. I just decided to redraw some stuff/adjust the distance and it eventually worked.