The trade to and from Danzig wasn't on Polish ships either.
That I can't tell besides the facts that (a) Danzig was a member of the Hanseatic League, (b) that it is an open question if what was exported from Danzig would be of interest to the Ottomans and (c) that the Ottomans did not have a big merchant fleet on the Black Sea.
So that's really no change.
Actually, there is: in OTL the Polish ports had been open to all foreign ships while in AH the Ottomans would have a monopoly on buying the Polish merchandise.
Then again, there is a massive market in the Ottoman Empire. When did the trade between France and the Levant get prohibited Alex - it sounds like there was a demand for grain in Constantinople around that time at least?
You are seemingly confused with what I wrote. There is a long list of the items that the French, Brits and Dutch had been importing and exporting. At some point selling
grain (one out of many items) from Levant to France was prohibited but did not stop.
I am currently reading an economic history of the Ottoman empire. I need to go further in before I can say more, but at this point I can still say that the trade route between Lvov and Constantinople was more important than the trade routes leading to the Mediterranean for Poland.
Anything would be more important than non-existent Polish trade routes to the Med and as for the rest, "the Crimean Khanate, vassals of the Ottoman sultan, enthusiastically engaged in the locally destabilizing Black Sea slave trade resulting in the disappearance of some 2,000,000 individuals from this frontier region between 1500-1700 "
http://poloniaottomanica.blogspot.com/p/overview-of-polishottoman-history.html
On a more positive note, yes, it existed and in the late XV the Walachian merchants tried to divert traffic from Lwow-Akkerman line to their own territory. I found list of the items that the Ottomans had been selling to Poland and Muscovy ("oriental goods" and wine from Greece and Italy) but pretty much (so far) nothing about the Polish goods except for
reselling the woolen cloth produced in Germany and Netherlands (most of the goods produced in Germany and Austria were going through Transylvania).