Cryptomatte not separating some materials

I have a scene with 3 materials, each with a unique pass id but cryptomatte still mashes one of them together with the white. As a test I added 3 new materials to the scene, red, green and blue blocks, and set every single of the original 3 materials’ pass ids to 0. Now it still automatically separates the old two materials correctly (both with ID 0) and the new r,g,b blocks correctly into their own flat colors, even with just the CryptoMaterial00 node connected and none of the others.

I can still use the pick function to select the “fence” material and see its effect on the matte node, but it never gets a color in the “pick” node. I tried upping the levels to max 16 and connected each of the 7 CryptoMaterial nodes correctly, but it makes no difference.

My only goal is to export the clown pass for selections in Photoshop and people said this is the easier way to do it rather than material pass, which didn’t work either. The white objects (ground and middle vertical blocks) are supposed to remain white as they have no material assigned and are of no interest to me.

Cryptomatte IDs are based on either the material data or objects. Pass indexes have nothing to do with Cryptomatte.
The idea of using Cryptomatte to generate a ‘clown’ pass is…clownish. Also, you can’t properly export Cryptomatte through output nodes despite what you may have read/seen.

The modern/correct way to setup masking in Photoshop is to disable the compositing nodes and render out a multilayer exr. Then use https://www.exr-io.com/ to access the layers and Cryptomatte Data.

When trying to render the IndexMa pass among others into exr, it just does a 2 value render with every material being the same white. I made one of those randomised emission color shaders because that seems to be the only way this can be done, still, but that seems to only work for different objects. As soon as I use the Material Index output to set the color and override the scene using this material, every single object becomes one color.

Is there no addon or something that does this? Even the pointlessly laborous manual way isn’t working.

It now seems that the exr material index pass which looked like white did contain different color values and was just clipped white, and if I compressed the dynamic range enough with a levels layer in photoshop (lower the white output level) I could get those values visible, and then convert it to the workable 8 bit mode so that magic wand becomes available.