I'm attempting to rid on the separation lines in my 3D model which appear between my exterior walls; however, I do not want to turn off contours. I have made sure all the walls are connected (more times than I can count) but the issues persists. These are custom profile walls for a unique project (hoping that is not the issue), all the walls are on the same layer, same custom profile, same material etc. It just doesn't seem to work.
Did you try to delete the curved part of the wall and connect them using the Fillet/Chamfer tool ? It should works for me as expected - Except - on Complex Profile walls, and for that it is only a matter of texture alignment, I don't see the lines where the walls connect. Those are some unusual materials. If it is just a different texture you want on the step riser surface you can show that without using a wall as is selected in your screen shot.