I have this strange issue, please refer the image below.
I have created a concrete path with raicloner, then there is a grass field on both side of the path, there are several bushes too but the problem is only on the grass. because I made the grass to be clipped by the spline that limits the area of scatering.
You can see that the grass is clipped but still produces a shadow where the original patch is located.
If I delete or hide the concrete path and use a simple plane, there are not strange shadows, this strange shadow only displays when there is a combination of raiclone and forest with the clip option.
your help is appreciated.