"google is not defined" on map for custom post type

I’m trying to get a map with all the posts for a custom post type called “dialisys_center” and I’ve implemented my own shortcode to achieve this using the wpgep_map() function with a custom $query array, like this:

/* Full map shortcode */
add_shortcode( 'dialisys_map', 'dialisys_map' );
function dialisys_map() {
	if (class_exists('WPGeo')) {
		$wp_geo_options = get_option( 'wp_geo_options' );
		$query = array(
			'post_type'		=>	'dialisys_center'
		);
		ob_start();
		wpgeo_map( $query );
		return ob_get_clean();
	} else {
		return '<p>WPGeo not present</p>';
	}
}

I’m getting “google is not defined” on google.maps.event.addDomListener(window, "load", wpgeo_render_maps);

Seems like the Google Maps API is not being loaded.
Any ideas why?

https://www.ads-software.com/plugins/wp-geo/