Millepora, easy or hard?

[Timbits]

I really really love millis especially their stringy polyps but I got one before and it just died. I wanna try again but I'm scared. Are they harder to keep than other sps like birdnest and montis? I have Ora green birdnest that is growing like crazy, rainbow monti, sunset monti, pocci, digi, bunch of other birdnests all doing well. Not sure why I can't keep millepora are there any special requirements thanks