Further update: the seat belts are anchored to the bottom of the slide-out living room floor on the very outer edge (visually hidden behind the outer edge of the slide-out that overhangs the main wall, unless you get down on the ground). The slide-out roller was installed at a location where one of those bolts would hit the outer slide roller when the room was moved in, knocking it out in relatively short order.
bclemens - this should be reported to the production line. Either the anchor bolts or the slide roller needs to be moved. In this case, it was the front roller but it could have happened to the back roller too.
2016 Forester 2401R