The filter works fine if dont select the sort by price, if i select the sort by price and when trying to use the price filter the URL set the value of the filter in a wrong place in the URL and that makes the filter doesnt work correctly.
How the URL should look:
/products.html?&price=100-100&product_list_dir=desc&product_list_order=price
How it actually look when the sort by price is selected:
/products.html?&price=&product_list_dir=desc&product_list_order=price100-100
I think that may happen because the URL has 2 paremeters named as price and magento may confuse where should set the value and actually is setting the value in the price parameter of the sort by.