[Balanor]

(And I remember reading how moving chests or other containers will "erase" the contents until the container is returned to the exact spot where the items were placed in it. Is that essentially what happened here?)

No, not really. Persistent storage in a player-owned building is determined by the containers exact location, plus the tag of the area. In the case of this problem, the area tag is wrong which is causing nothing to be retrieved. But whatever you do - *don't* remove/move any of the containers that had items in them or then they will be lost forever. Following the steps above will get you in the correct area with the area tag, and once that is done, as long as the position of your containers hasn't moved, your items will be retrieved for them so you can pull them out and store them when you enter the area with the default tag (ending in the number 1).