Loripes/granulosas....don't die, just turn brown and sit there like a lump forever, sloooooooowly recede. Really stinks because they are one of my favorite corals of all time.
Same issue with birdsnest here. But I don't really mind that much, they don't do it for me.
Also encrusting montis. Could never grow sunset, finally got a superman (sold as original pokerstar for waaay too much money) to recover from 5 polyps to a 5" colony over the course of 5 years, color is not the best though.
Knock on wood I have 2 abrotanoides and 4 spathulata frags going strong though! Should be awesome colonies in about 4 years! :)