searchsource/sourceProductCategorySearchFilter is not responding to modifiers

Summary:

Content (required):

I have the following in my answers/list.php but it has no affect in how the product and category interact.

The product is still dictating which categories are visible to the user, i.e. they are still linking. In addition the "No Value" option is not showing in the drop down list. What am I doing wrong?

Version (include the version you are using, if applicable):

21B

Code Snippet (add any code snippets that support your topic, if applicable):

<div class="rn_SearchFilters">

          <rn:widget path="searchsource/SourceProductCategorySearchFilter" 

enable_prod_cat_no_value_option="true" 

linking_off="true"