So, just to prove that this is a printer issue, print something else using the same printer setup (same rear tray feed, paper settings) and look for that band at the same place on the paper. When I say something else, I mean perhaps several smaller images that will appear at the same paper location and see that the light band goes through all of them, or a small black box, or text document, a page from the internet, whatever.
I don't have that printer; perhaps someone on this forum who does can chime in here.
I agree it is a almost certainly a printer / driver problem. I printed a 12x18 print on 13x19 Hahnemuhle FineArt Baryta Paper and encountered no light line... The driver setting for this paper is "Other Glossy Paper" while with the problem matte paper it is "Other Fine Art Paper 1". So its something to do with that exact paper type / settings. I am out of the problem type of paper until my shipment tomorrow when I can test again but this is costing me a fortune in ink and paper!
I will report back later unless someone comes up with something in the mean time... Thanks to all for helping me work through this, I'm still learning Qimage and only been printing for a year now so this troubleshooting is new to me...
Benjamin