If you don't run the gloss optimizer over it you really can't tell what you are getting. You might even need to pump more (or less) of it onto the paper to get the right results. Another option is to do a couple coats of Hahnemuhle protective spray instead of the gloss overprint. I've found that has done a better job and produces a better feeling print than the GO. You do need to let it dry overnight or blow dry it for ~5 minutes before over-printing/spraying. I can't log into the IJM forum right now to see the attachments but will try too look into it more tomorrow.
I all but stopped using gloss/PK papers with Peizography—not that it wasn't good (with the selenium inks), but I have been using the Cone Carbon inks for the past several months and I don't like how brown they are with Canson Platine. When it works, it works beautifully, but I've never seemed to be able to make the shipped piezography profiles work for me or my printers. I've chalked it up to aging or out of spec printers, but it seems more and more people are having similar issues these days (or maybe the issues are just becoming more apparent).
Are you able to try a P2 gloss profile with that paper and see if that has similar problems? How are other gloss papers responding?
Richard Boutwell