Dan Lee

Hi. Can you file a bug with an example .hip file please?
Thank you!

Hi. You're likely seeing internal reflection which is contributed by transmission lobe via fresnel factors, so they can still appear even if you disable specular. There is no clear separation of tasks for transmission bsdfs for total internal reflection (which we want) vs other internal reflections (which we don't want). This is something that we will address in upcoming major release, but currently there is no plan to backport to 19.5 and earlier due to compatibility/look preservation.

Hi. Are you referring to the checkerboard appearance? RGB channels are only for preview and uses checkerboard to indicate selection. Alpha channel contains the output mask. Please see https://www.sidefx.com/docs/houdini/nodes/cop2/cryptomatte.html [www.sidefx.com] for more detail.