This only seems to be a problem with the forward renderer.
Steps to reproduce:
- Create a new project and enable forward rendering.
- Create a basic light function material (I used a simple noise node)
- Create a point light in the scene .
- Apply Light function material to light.
- Toggle the Cast Shadows box on and off to see the effect appear and disappear.
It makes no difference if the light is static or dynamic.
I’ve attached a screen shot of two point lights, the left one doesn’t cast shadows and the right one does.