Invisible fridge - buggy or just my game?

I have a weird thing which keeps happening with the mini-fridge from Uni. (It has happened on at least 2 of my lots, in the same neighbourhood, and happens even if I sell the fridge and buy a new one)

Basically, when a sim uses the fridge, it disappears, but they continue to prepare the food and serve it. When they pick up the plate to "serve" it appears momentarily (ie in their hand) but as soon as they put it down on the invisible fridge, it also becomes invisible. All sims can take food from the plate with no problems, but I can't click on it or pick it up to delete it. I tried using the stuck object remover and that made the game crash. This has happened twice, on two separate lots.

This was puzzling and annoying me for ages, and then one day I happened to zoom out and noticed that right in the far corner of the lot, actually off the lot, there was the fridge, just sitting there. I went into buy mode and picked it up and for a second the green placement square flashed on the square where the fridge was originally placed, and then it snaps to where the cursor is, and is red because it is outside the lot boundary. I can move it back into its original position, and it works fine. Or, I can leave it in the off-lot position and sims continue to use the invisible fridge.