Index: src/includes/replies/functions.php
===================================================================
--- src/includes/replies/functions.php	(revision 5935)
+++ src/includes/replies/functions.php	(working copy)
@@ -1002,8 +1002,8 @@
 					bbp_update_forum_last_active_time( $ancestor, $forum_last_active_time );
 				}
 
-				// Counts
-				bbp_update_forum_reply_count( $ancestor );
+				// Counts -- bump up the reply count by one and only do it for this specific ancestor.
+				bbp_bump_forum_reply_count( $ancestor, 1, false );
 			}
 		}
 	}