Shadows doesn´t render correctly when a map is addded to the Refl.Glossiness.
The shadow improves as I reduce the amount of the refl. glosiness map. This improvement seems to be affected by the distance to the object casting the shadow.
See attached image.
Notes:
The shadow comes from a proxy tree in this example, but the problem occurs with regular objects as well.
My conclusion is that any changes on Object properties as Cast shadows or Visible to Refractions/Refractions will create wrong results on top of objects with a Glossiness different that 1,0 (regardless if it is a map or just a number). it will basically show shadows, more or less dense, while Cast Shadows is unchecked.
This is a significant problem in archviz, especially for those planning to create fake shadows or fake reflections inside the 3D scene, to later add objects, like trees, in Photoshop.
In the case of Corona Render 8, the same happens to us, but if you change the ground material to a Physical material, the shadows will appear correct. Try it and let us know if it improves. In our case, I think it happens without having objects hidden from the camera.