FacetWP page shows no results with the modal as a menu-item

[m-e-h]

My existing Facet pages stop working once I activate this plugin and add the search menu-item.

The pages are set up on archive posts with their own facet search boxes.
All posts show initially but, in my case, once a "proximity", "alpha", or "search" are selected I get 'No results found'.

I've tried both the default and searchwp options for the Search engine in the FacetWP settings.