Index: wp-includes/query.php
===================================================================
--- wp-includes/query.php	(revision 21544)
+++ wp-includes/query.php	(working copy)
@@ -2216,6 +2216,16 @@
 		if ( $this->is_tax ) {
 			if ( empty($post_type) ) {
 				$post_type = 'any';
+
+				// do a fully inclusive search for registered post types of queried taxonomies
+				$tax_post_types = array();
+				foreach ( wp_list_pluck( $this->tax_query->queries, 'taxonomy' ) as $tax ) {
+					$tax_post_types = array_merge($tax_post_types, get_taxonomy($tax)->object_type);
+				}
+				if ( !empty($tax_post_types) ) {
+					$post_type = array_unique($tax_post_types);
+				}
+
 				$post_status_join = true;
 			} elseif ( in_array('attachment', (array) $post_type) ) {
 				$post_status_join = true;