I think it might be too much light. I had mine on a frag rack pretty high up so I lowered it to mid tank level, about 12 inches lower and have seen mine make a comeback.
i think alot of people will say it needs way intense lighting but they dont realize that we HAVE crazy intense lighting already so that has to be taken into account. I'm having this issue in my 60g cube with the new LED
's so I think we may have more light than it actually needs. Also the flow is very important with these corals too so make sure he is in a pretty high flow area, not directly on it of course but enough flow to keep it moving.