I'm here three and a half years later and having the same problem. But in my case, the door is locked....
So I have a pair of brothers and their families living on the same lot and I built a duplex for them. Everything in the building is identical and mirror image.
Down to the issue; Sometimes I tell one of my sims to cook something and the start, but stop halfway through. I kept trying and trying, and I couldn't figure out what was wrong. Then, I thought to unlock the front door to the other half of the duplex. Sure enough, my sim takes her half-made cake, walks over to the kitchen on the other side, and puts it in the oven there.
I would like to stress again, that the kitchens are identical (Same counters, same appliances, even the same layout), but for some reason she didn't want to use her own oven.
I would appreciate any help you can offer.
