Bingo! That was the key...
I'd been trying the paper type -Canon Pro 100 full printable CD/DVD
and needed to instead use the Canon Pro 100 printable CD/DVD
Once I did that, the printed disc was perfect right to the millimeter!
I'm not sure what the former one is for, but just so I have the right one, that's all that counts.
Thanks for the help. Great product! I'd been using the demo version and purchased it after getting things to print properly.
Just another thought.... What is the "full printable" version of this template supposed to do? Might it be better to give these templates names that would better describe their correct application so users would know which to use?