Plate of food stuck and invisible now in a room!

I've found that if a sim is already heading to a room while I'm locking the door, they are able to get in but then they are stuck in there. As for the plate, do you have any shelves on the wall? I once used the wall shelves from Island Living in a kitchen and after playing for a bit I raised the walls and the shelves were covered with stinky plates and glasses. Lesson learned: if I use shelves in the kitchen I make sure to add decor items to all the slots.