I think my sim has become psychic, she can see things in other dimensions, during a festival she made herself a snowcone from an invisible snowcone machine.
And i've just been playing about with the seasonal lot markers trying to make my own festival lot, in all seasons I have tables and chairs but for when the festival isn't happening I have community picnic tables. So I put my teenage sim in to test the lot out and straight away found a problem, she keeps trying to do her homework on the invisible tables.
It seems even though things get hidden sims still know they are there