We are having trouble figuring out, why cryptomatte does not show up on IPR aswell as Nuke. There seems to be working data in the files rendered, but it's not beeing displayed correctly. We are rendering 32bit EXR files, drivers are set to EXR aswell. No merged AOVs, not multi-exr. Did anyone make built in cryptomatte work yet?
The preview AOVs are deprecated, so all that are left are the data AOVs that look weird. The way to tell if it's working correctly is ultimately to try keying it in Nuke using the Cryptomatte node. Does that work?
Cryptomatte is disabled in the IPR and PV since C4DtoA 2.4.0 because there is an issue with the preview AOVs. It's allowed only by an Arnold EXR driver. After a quick test the EXR rendered in R20 properly contains the cryptomatte AOVs.