WP query using ‘eventful=1’

Hello, I’m finding Events Manager very useful for a few websites, so really appreciate all who’ve worked on it!

I’d like to produce a list of all future events grouped by location, and so I’m writing a WP query as follows:

$args1 = array(
	'post_type'=>'location',
	'eventful'=>1,
	'tax_query' => array(
		array(
			'taxonomy' => 'area',
			'field' => 'slug',
			'terms' => $area,
		)
	),
);

$query1 = new WP_Query($args1);

However, “‘eventful’=>1” does not work as I get a list of all locations.
Do I need to use a meta_query, and if so, what?

(Using EM_Locations::output() works for “eventful” but not for my custom taxonomy).

Thanks for any help.