Index: src/bp-activity/classes/class-bp-activity-activity.php
===================================================================
--- src/bp-activity/classes/class-bp-activity-activity.php	(revision 11242)
+++ src/bp-activity/classes/class-bp-activity-activity.php	(working copy)
@@ -455,7 +455,7 @@
 
 		// Sorting.
 		$sort = $r['sort'];
-		if ( $sort != 'ASC' && $sort != 'DESC' ) {
+		if ( empty( $sort ) ) {
 			$sort = 'DESC';
 		}