My coral beauty angel has eaten very well since the day she went into the tank...almost a year now. I've always given her Formula II flakes with garlic, plus, of course a variety of other things after she acclimated to the tank.
How long has your beauty been in the tank? If you just got her, it could be she just needs to establish herself in her new environment...Oops, sorry just reread your post. Give her time. What other tank mates do you have for her? Tank size, etc.? Acclimation process? These things can all impact the time it takes for her to get comfy.
Good luck, and keep us posted.
Lisa :happyfish