Cryptomatte outputs one or two colors only This may be me just being a Blender noobie, but when I try to render a Cryptomatte pass I only get one or two colors, usually green or white, with full alpha transparency for some reason (I had to check in the Image Editor to show RGB only so I could at least see what the pass rendered). The other passes seem to render OK, though.

Is there a setting I need to check or is it a bug? I'm using Blender 2.81a. Thanks in advance.
It's because you are using the pick plug instead of the image or matte plug