I have a bunch of 3D precomped layers which are stacked underneath some other layers. I want to add an adjustment layer above the 3d layers but when I add one its ok if its at the top but if drag it down to sit above my 3d layers they turn invisible. Not sure why. There is no effect on the adjustment layer. I can still see thir outline but the image disappears.
Adding an adjustment layer between 3D layers changes the rendering order and causes some of the layer's properties to change. Please tell us more about your composition and/or provide a screenshot revealing the changed properties and effects of all layers so we can get an idea what is going on.
What Rick said. 2D layers asked as "stoppers" in a 3D environment as do things like layer styles. Normal behavior.