Mobile Preview Modulated Shadow Bug?

I’m creating a scene where I would like cast shadows on a mobile platform. I’m using a single, stationary, directional light source with modulated shadows. My in-editor preview window is set to the Android Preview with all engine scalability settings at Epic and everything looks fine there. A compiled and packaged project run on a Nexus 5 also looks fine. The Mobile Preview, however, has a rendering bug:

If you look at the shadow of the crane arm, it appears to be clipped by some invisible line. The orange box it is holding though does correctly cast a shadow onto that surface. I thought at first it might be related to the underlying geometry of the gray quads that make up the surface, but I’ve overlaid red lines on the image to indicate where the triangles are and there is no correlation with that or with any other geometry in the scene. Moving the camera around the scene also does not change this apparent clipping line.

As this does not appear to affect the final compiled output, it is mostly an annoyance at this point, but it would be nice to correct if it is just a settings issue. If this appears to be a bug, I’m happy to try to decompose this further to assist finding the root cause. Thanks!

New project with desktop target, maximum quality and share model 5, and I’m seeing this same issue again:


Any thoughts?

One more thing I noticed, if I turn on “Single Sample Shadow from Stationary Lights”, it crops the shadow further… it is definitely related to the stationary setting of the light source.

the preview lighting is just like that. I don’t think there’s really anything you can do about it. Sorry. Try building a higher quality lighting, and see if that helps. If it does, then I think you will just have to deal with it. BTW whatever it is you are making looks pretty neat.