Hello
in order to see the problem Try on your demo but Set up for friendly urls, and set 4 products per page ( the problem happens to whatever number of products but here we need a setup to be able to have next pages )
So then select women on top menu
then from filters on left select something with more than 4 products. you ca test the new products filter or the fashionmanufacturer
Then you see the results
BUT you will not be able to see the 2nd page of the filtered results
once you hit the page number 2 or the next button it changes the url to the generic category url
it is a BAD bug from prestashop too and makes sites unable to sell if there are filter criteria with many results.
it would be great if you could solve it
Best Regards
dynamics