I find it interesting that they failed one at a time. I think its a vacuum issue of some kind. The door farthest from the rear vaccum pump failed first, then the one next farthest (drivers rear), then passenger front, leaving only the one closest to the pump still working. It doesnt make a lot of sense, since default position is unlocked/no vacuum. But I have a hard time believing that three door latches all failed mechanically, one at a time.

Can a slow vacuum leak contribute to this problem. Probably not. But could the pump be working too well? So much vacuum the actuators cant hold it back?