I've this problem with the 3D effect: the vertical lines projected by the effect aren't vertical.
I start with a plane shape like a rectangle and I select the isometric top preset in the effect and this is what it happens.
In the isometric view the vertical lines are supposed to be perpendicular to the ground, right? I mean, if I draw the same shape in the isometric grid the vertical lines are really vertical. I miss something.
The object in the image is the same but reflected for a view of the problem.
Thanks for the attention.