Hmmmm... interesting. I've copied your invocation step and it works.
The difference is in the interpretation of what the manual means when it says a parameter is "optional". I interpret that as meaning "I don't have to specify it if I agree with the default". However, that does not appear to be the way CONPARMX works. I originally coded my PARM list as:
PARM=(IGYCRCTL,,$$$$DFLT,&C1PRGRP,,). I then tried various combinations of including null parameters up to and include PARM8.
To make a long story short, what I've learned is "none" of the parameters are actually "optional". They all need to be specified and accounted for in the PARM list provided to CONPARMX. I even tried PARM=(IGYCRCTL,,$$$$DFLT,&C1PRGRP,&C1ELEMENT,,,) where I would have assumed it would work with default values for PARM7 and PARM8... nope. I also tried PARM=(IGYCRCTL,,$$$$DFLT,&C1PRGRP,&C1ELEMENT,,'N',)..... nope.
It wasn't until I FULLY qualified every PARM field that it worked: PARM=(IGYCRCTL,,$$$$DFLT,&C1PRGRP,&C1ELEMENT,,'N','N')
Thanks for your help! It would have taken me a lot longer (and a trouble ticket with CA) to figure this out without it!