I've attached a file (VW2018) which contains a site model object, with a few site modifiers applying to it. In plan and OpenGL 3d view all is fine, but when I take a section through it (see the section viewport on the sheet layer) It's a complete mess, with multiple section lines all over the place.
The problems with this started out with it refusing to show fill in certain sections. Then, it refused to show fill in any sections. Now this.
What has gone wrong and how do I
Here's what one of the site modifiers looks like when I select "show 3d".
Half of it sits on the surface of the model, and half of it seems to be at zero elevation. I don't understand how it's ended up like this. I don't know if it matters, but I suspect it does and is linked to the problems. I don't know if there's any way of fixing it other than tracing over it with a new modifier, and then deleting it.
The effect of this modifier is as it should be, when I look at the