Hi, Corey. I will try to re-explain; the shadow matte seems to be set up correctly already with -1 alpha contribution, as you mention. The problem is that it only works when I DON'T render from behind the glass. When I render from my camera setup inside the apartment, you look through the living room windows, onto the exterior and onto the shadow matte, but the shadow matte isnt displayed right... In attachment image 1 you see its working fine, but in image 2 you see the shadow matte from behind a window and that's where it's not working. (completely solid white in alpha channel)
I know a solution would be to hide the glass and do a separate render, but there has to be a logical solution to this...
If anyone need any screenshots of anything, just let me know. I've already tried setting the glass material's refractive channel to "affect all", but that didnt work..