Unfortunate! I think when more items are added this issue will be fixed. And yes it seems like 15+ might be bugged, will be addressing it soon. Mad props for getting there! that will definitely be a rare steam achievement in the future!
I think it says a lot that I played until then! If I might make a suggestion, I've noticed plushies appear on the cameras, perhaps hiding them around and clicking on enough of the same character plush could guarantee that plush being buyable at the end of the night, or perhaps unlock it outright? Just a thought, keep up the great work!