Just checked, you have this problem even on your demosite:
https://www.8theme.com/demo/royal/?product_cat=accessories
If you go to the single product page of the fist listed item (the blue pendant) and then use the navigation buttons, the order is as followes:
– the gold ring (right)
– the necklage (right)
– the silver ring (right)
But then the navigation stops and you think that that you have reached the last item. But there are still the earrings, the bags and so on and you will never detect them if you will not visit the main shop page. I think that this is really a big problem and any help how to fix this would be really appreciated.