Index: src/wp-admin/includes/class-wp-comments-list-table.php
===================================================================
--- src/wp-admin/includes/class-wp-comments-list-table.php	(revision 33776)
+++ src/wp-admin/includes/class-wp-comments-list-table.php	(working copy)
@@ -78,7 +78,7 @@
 
 		$search = ( isset( $_REQUEST['s'] ) ) ? $_REQUEST['s'] : '';
 
-		$post_type = ( isset( $_REQUEST['post_type'] ) ) ? sanitize_key( $_REQUEST['post_type'] ) : '';
+		$post_type = ( isset( $_REQUEST['post_type'] ) ) ? sanitize_key( $_REQUEST['post_type'] ) : get_post_types();
 
 		$user_id = ( isset( $_REQUEST['user_id'] ) ) ? $_REQUEST['user_id'] : '';
 
Index: src/wp-admin/includes/dashboard.php
===================================================================
--- src/wp-admin/includes/dashboard.php	(revision 33776)
+++ src/wp-admin/includes/dashboard.php	(working copy)
@@ -796,7 +796,8 @@
 
 	$comments_query = array(
 		'number' => $total_items * 5,
-		'offset' => 0
+		'offset' => 0,
+		'post_type' => get_post_types()
 	);
 	if ( ! current_user_can( 'edit_posts' ) )
 		$comments_query['status'] = 'approve';