filtering on multivendor site

Hi,
I’m using Woof filter on my multivendor site using WC Vendors. It works well on category pages. If I use it on individual vendor pages (automatically generated by WC Vendors using the product archive), the filter works but includes all products and not just the products of the vendor when using the filter. Is there a way to have the filter preselect the vendor (author’s) products as options to filter only?

Thanks