The shadow keeps appear in the box itself. How do I fixed it?
I don’t use 3d boxes, but seems it’s the same problem than in 2D : your object has the “light obstacle” behaviour ? If yes it seems normal.
So there are no solutions to this issue? 
Try to put the light under the 3DBox (lower z-order for the light).
Its not working. The shadow is still overlapping the 3d object itself.
The light is a global light.