Try keeping ph around 8 or so. Mine seem to do better with that. Since you you have a mixed reef, you should already e watching that. Some people just have bad luck with them. I can't keep Euphyllia at all, and my buddy can't keep a zoa or paly alive at all....go figure.
You could try spot feeding or d of broadcast based feeding. Softies seem to like iodine as well, so you could try a LIGHT iodine dose. Careful cause that stuff can be dangerous if not used correctly.
Do you treat the tank with any additives at all or do any feelings? What is your lighting like?