[Plugin: Query Multiple Taxonomies] Filtering via 'Categories' gives no result.

Hi,
I’m using the latest Alpha version of this plug in and I’m using the widget to offer filtered searches via the drop-down menus.
On my widget I have ‘Category’ from the WP default, and my custom taxonomies ‘Sector’, ‘Region’, ‘Environment’, ‘Technology’ and ‘Purpose’.
I can do multiple queries on all or any of the custom taxonomies, but if I try to simply select one of my WP Categories from the drop-down menu on the widget and hit submit, I get returned to the home page even though I know I have articles in that category. Similarly, if I select a category and one of my custom taxonomies and hit submit, then it will filter based only on the custom taxonomy, not on the category.