Dropdown Menu Error with Productfilter

Hello,

I am working with the free version of YITH Product Filter. When I try to filter the products on the webshop the dropdown menu does not work properly.

When I apply the filter, the view of the dropdown menu changes. I work there with arrow symbols, which disappear or are doubled when using the filter.

Does anyone else have this problem?

The page I need help with: [log in to see the link]