For 3DsMax Vray, now there is an option to save Cryptomate in a separate file, only the cryptomatte.
This won’t work nice if the render is set to render localy ( and then copy files when finished )
The cryptomate won’t end up in the output folder.
As a workaround I’m de-activated the “render local” option in deadline and that seemed to work, but maybe in certain situations that could cause overload of the network and make a render fail? won’t be my case though, but well thought to mention it, just in case that you could give it a look.