Material Wrapper - Shadows Function Not showing Shadows

[casey_lewis]

I am attempting to create an alpha channel by creating a matte ground plane via material wrapper and preserving shadows. When I click shadows the render starts off with shadows while it builds light cache and then in the first render pass the background turns white with no shadows, see first image. See second image for my settings.

Am I going about getting an alpha channel with preserved shadows incorrectly? Why is it that when I click shadows in material wrapper editor I get a blank background? Any help appreciated.

[Micha]

Do you use light sources or the standard environment? The shadow alpha works with lights only, for example a dome light could help.

[casey_lewis]

Thanks for your response, much appreciated.

Yes, I've been using light sources. I have turned off my standard environment and am only using a dome light and I still get the same results. See attached for a views of the asset editor.

Any other ideas of what I may be missing?

[Micha]

Today I opened an "old" project from last year. There was an shadow receiver setup and now the shadows at the alpha are missing. I load a new shadow receiver material from the library and this works. Please try this too.