Steve & regal,
I can't pinpoint why I have problems with Chevrons, I also thought that they were not a difficult fish to keep in captivity.
They're almost similiar with the bad track record I've had over the 20 + years with these two other fish from Hawaii: Potters & Achilles.
Some do well for a couple of months then dead, some never get going from the beginning.
I've limited myself over the years with these 3 species but every now and then (like now), I get an itch and think that I'm a better educated hobbiest in terms of care but the Chevron has kicked my butt 4 x in the last 13 months.
In particuliar with the Chevrons lately, all of them were not hearty eaters but they did pick at food. They all went into established reef tanks and picked at the rocks and accepted some prepared foods.
I must be doing something wrong, yet when I purchased my Golden angel, he didn't take to prepared foods for about 2 months yet survived on the LR & my Regal angel also didn't start eating prepared foods for 3+ weeks and also survived picking off the rocks.