I have the same issue - glad its not just me, but as it happens when you just drag in Volumetric Clouds, I assumed it was a setting - having played around for a while with all the settings, I cannot get rid of it. Is this really how it is meant to look? Because it looks pretty terrible, unless you aim the camera in a direction where the seams and tiles are not visible. If anyone knows how to fix (or if it is a bug) it would be good to know.