Maybe you could change your prefs first to V2 profiles, then optimise the profile in question. This should revert it to a V2 profile , thus you'll eliminate this blue defective background zone printing.
I tried this, but only succeeded in crashing the ColorMunki software.
Rather than build a new V2 profile, I tried an old Canson-supplied profile, and it works fine. When I checked the Canson web site, the profile they now supply is V4, but luckily I had an old one on my disc, even though I wasn't using it.
Not sure why I was seeing this for the first time now. Maybe I hadn't done any printing since the 10.6.7 upgrade, but I definitely did under 10.6.6, and I hadn't seen it then. Ah, well.
Thanks much for the help, Jeff, Neil & Alan.