I don't have any personal experience with this so bear with me, I am just going off of what I learned from biology.
When you simply put the anemone in the brightest possible spot, it was the equivalent of you being in a dark room for an hour or so, and suddenly having someone shine a spotlight in your face. Your eyes have to adjust, so you would
A: close your eyes and
B: get away from the light for a little bit
That is exactly what your anemone is trying to do, adjust to the light.
You should just wait for it to turn up, and when it does, reposition it in a spot that is the same distance from the lights.