I have been playing around with this issue for a while and am wondering if this is a limitation of rendering currently or an issue with my setup. I have a scene with a single character I’d like to render to a PNG with an alpha channel behind. This works fine, Now the issue comes when adding a Scene Depth and MaterialAO render pass, again, the beauty/main pass renders fine, with Alpha, but the Scene Depth and MaterialAO passes do not render properly when alpha is on. They are completely invisible, no character, no information at all. When I disable alpha for the png, all renders appear fine, of course with no alpha.
Does anyone know if this is a current limitation or if there’s a setting I’m missing? As a workaround I’ve rendered a separate pass to use as a mask for the additional passes but it would be really nice to have a clean alpha for the additional render passes.