3D issue. Z position is not accurate. Objects come on top of each other.

[Carolie260966150k3y]

Hi, I've been running into an issue which I can't seem to find an answer to, nor find help online. 
I hope someone out there can help me! 

I have designed a 3D space with flat 2D illustrator or png files in it. 
My 2D images each have a different Z position in the space, some further and some closer to the camera. 

Although the Z positions are the right ones on my position settings, they seem fine when I look with the top or side view, but when my camera comes in front of two objects, the further away goes above the closer one, as if it was closer. The Z position don't seem to work anymore. 

See in the screen shot, the red truck, the trees and the beige stadium on the right, all come above the little market in the center.

And in the other screen shot, the mountain with the yellow cross comes above the wooden arch, when it is technically behind it. 

I'm kind of going crazy over this. Please help !
Thank you so much! 

[Mylenium]

Hard to say without more specific info, but the first thing to look for are effects, layer styles and so on on the layers that may break 3D rendering. I can't make heads and tails of it, but there also appears to be a somewhat wild mix of collapsed and regular 3D layers which may need re-ordering.

Mylenium 

[Roland Kahlenberg]

The top two layers in the ScreenCapture, Layers with Index 62-63 are nested compositions and they each have at least one effect AND they also have Collapse Transformations enabled. Try disabling the Collapse Transformations to see if this fixes the issue. You will want to take note that if the Parent Comp (the originating comp) contains 2D layers, and if this comp is nested, the 2D layer(s) will prevent 3D calculations for 3D layers. The end result will be a composite of 2D layers since all the 3D layers will be treated as 2D layers when you Collapse Transform and the originating comp has a combination of 2D and 3D layers. 

HTH