Attribute Slug

Hello
I have a prob with the Attributes slug.
If i write the slug with Greek characters the widget filter works but when you trying to disable it via x icon its only refresh the page without remove the previous selected filter. (with the widget WooCommerce Layered Nav Filters)
Like:
http://www.domain.com/shop/?filter_greekword=attribute

If is set the slug with greeklish characters or in english it works perfect.

https://wordpress.org/plugins/woocommerce/

Any help?