It's either easy or hard to keep. Can't be both. Usually there is just one simple change that changes it from hard, to easy.
Like blue ribbon eels, for example. They were "hard" to keep (would not eat) because they would just stare at the food you gave them until they starved. Until in 2006 or so, when I discovered that all they need is a long tube to hide in; if they know that their long bodies can't be seen and thus eaten, then they have no problem grabbing silversides from you. All that was needed was a piece of pvc pipe longer than their body (3+ feet). Just google "my blue ribbon eel eats!".
So the blueberry gorgs are probably the same thing... some small parameter or food particle is missing.
I use a mixture reef roids,ultra seafan, r.o.e,phyto feast and oyster feast it feeds all my coral and they love it especially the sea fan it likes a variety of foods so i think i covered all the bases lol!!
I have mixed feelings about the freeze dried phyto products and the "dead" foods... Unless you have incredible circulation and no dead spots I found that I would always end up with problems. That's why I went with live foods. Copepods and now rotifers. I started the rotifer culture for seahorses, but was producing so much I started dumping them in my tank. The moment I poured it in the tank all of my corals would open right up and start feeding.
You can keep a culture running in a pickle jar or large plastic container (water 1 gallon bottle) with an airstone. I have one running and I would be more than happy to show you how and give you a starter culture. The only thing you need to buy is the microalgae concentrate to feed them.
The trick is to replace half of the culture every day with fresh salt water and to feed it twice a day. So if you have a gallon container you can be feeding your tank half a gallon a day of live rotifers.