Found this thread while looking in the Internet as we were assembling the Grand Emporium on Christmas only to be stuck at the flower ornament on the roof. I thought it was just us being novice builders who didn't get the instructions. But the flower described by the original poster is the same as what I have in the set. Attached is the flower ornament, it is not a hollow stud as it should be.
I have ordered a replacement from Lego, we will see if I have the same experience as the others with getting the same wrong part.I am not sure if it is an entire production batch that is affected or just a few who slipped through the net. Nevertheless, I do think Lego should investigate as these modular sets are not cheap.