Same problem. I was having some trouble closing the rear door (similar to other complaints on this board), so I decided to be proactive, and work with the latch mechanism and some WD-40. All was well, closed the door, drove to the kids school and found that once I opened the rear door, it will no longer latch.
Mechanism moves freely, just won't stay engaged. I'm still digging through the boards here, but will be tearing it apart tonight or tomorrow to resolve the issue.
Wish the OP would have provided an update/fix