Issue with 'Light function' on transparent material (GIFs included!)

I am using a ‘light function’ with my sun (a point light) to create cloud shadows across my landscape. It simply consists of a cloudy looking noise texture that pans slowly. It works great except for when it falls on an object with a transparent material. Here’s a GIF:

128047-incorrect.gif

On both the clouds and water planes in my environment, the light function seems to stretch weirdly over the mesh, causing this visible ‘striping effect’ as the light function pans across. The striping moves/jitters as the camera pans, too. However, the problem disappears/resolves when I get close enough to the object, and returns to what it should look like (a cloud texture passing over the object). This GIF shows what it looks like as I get closer (AKA what it SHOULD look like):

128049-correct.gif

Unfortunately, changing the Fade Distance value seems to have no effect on transparent materials. The light function is always present on transparency and only resolves at this seemingly arbitrary distance. PLEASE HELP! Any ideas/suggestions are greatly appreciated.