I have a terrain that i light mapped. I then paint trees on it and they should be casting shadows but arent. Im pretty sure it has something to do with the light map process like the terrain uses the light map instead of real time. I cant find where to get back to where i can paint trees on my terrain and see the shadows, the terrain options dont seem to have the answer. If i create a new terrain it has no problem with the shadowing.
You need to clear the lightmaps in order to have the terrain be able to receive real time shadows again. Clear the lightmaps in the Lightmapping panel.
That or you need to generate dual lightmaps so the near trees have realtime shadows