I am using Vuforia with NGUI providing 3d UI elements. The UI camera is a child of the AR camera, set to only see things on the correct layer.
The UI camera is drawn on top of the AR camera.
The UI is a child of the Image Target, with the relevant pieces set to the correct layer to be visible.
My issue is that the UI camera isn't properly displaying it's elements. They are there and interactable, but they aren't positioned properly with the view of the AR camera, they move as if the cameras aren't quite in the same position. If I add the UICamera script to the AR Camera object, I can interact, but it breaks all the default Unity interactions.