I too thought for some reason that photographs were not allowed, so I didn't take my camera. I noticed some people taking photographs inside and decided to try my luck using the camera on my tablet. I am quite certain the docents saw me taking pics, but no one said anything. Perhaps my innate persuasive charm? ;-)
It's allowed and it was always allowed you just have to buy a permit then you get a small camera sticker and can take as many photos as you like.