CryptoMattes: Do Object ID Passes Work?

Hiya, I’m trying to render an object ID pass in 5.2 but just get this…

It also comes fully equiped with the following images…
KD_01_EXActorHitProxyMask01main_camera
and KD_01_EXActorHitProxyMask02main_camera


So I get 3 unusable passes instead of 1 usuable object ID. Any ideas? Is it bugged? I tried with nanite off but got the same result. I also tried this with exr - like in the WIlliam Faucher tutorial - but no joy.

Cheers,
Adam