I can't post on the NSP thread for some reason. But just wanted to say that I have a similar problem to https://www.gavick.com/forums/255/wrong-link-54252
I have NSP active in 3 modules. Each module pulls K2 sub categories of one main category. Everything works Fine.
I have another NSP which pulls items from another parent K2 category. The thumbs + images display correctly but in the second category case the items do not open, the original page is reloaded.
EG:
index.com/category1/item/356-test works
index.com/category2/item/355-test2 returns to the module page.
I have change the K2 SEO settings and still the NSP link generation fails