
This doesn't happen in Standard render:

I had a search and found other people are having similar problems: viewtopic.php?f=30&t=55745#p285588, but couldn't find a solution that worked for me. The Ray Epsilon is 0.01, so not sure that has anything to do with it. My Camera focus distance isn't negative either, so run out of ideas.
I've uploaded my C4D file in case anyone wants to take a look: I am using PR5 on a Mac running Catalina
Thanks!