I'm pretty sure I have the setting as per guides from Harman.
BUT - and this is perhaps the answer to my question - what would a print look like if you used the profile for Glossy, and it turned out that the boxes got switched a couple of years ago, and what's in the box is in fact Matte? (It certainly doesn't look glossy to me, but then, nor do some of the Hahnemuhle 'Glossy Fine Art' papers I have in a sample pack.)
I just had a long conversation with the friend I got the paper from all that time ago, and he seems to remember something of this sort!
Would that have the effect of the blacks not registering as proper blacks? Maybe someone can confirm that this is the case - I'll then try the printer on matte black for the first time and hopefully, that will be it. I can then stop wasting your time on this one.
Thanks
Chris