Yeah, that's a bug that is already fixed for the next update.
Viewing post in Hotel Tycoon Alpha 3
Nice!
I've also noticed that the light goes through the walls, but since there are no roofs that might be it, or it may just be unity. No biggie really.
Other than that and cleaners cleaning the same room I dont find any obvious bugs.
BTW: The way the chefs work with stoves, could work for cleaners, they dont try to use one which is busy :)