Montipora problems

[Costareefer]

I have picked up 3x now montipora tropic thunder frags and everytime they shed their flesh usually over days. The one I added shed it over night. I added other monti species last night without problem but this one I have no clue what’s happening. 20ppm nitrate .03 phosphate alk 8.5 ph steady at 8.3. It makes zero sense I’ve been in the hobby for 25+ years and never seen anything like it. I run my AIs on a low setting so that isn’t the issue either. Very frustrating. All other montipora species thrive in my tank. Here the frag in question

 

[Reefing Madness]

 

[Joekovar]

My first thought is to wonder if you're getting the frags from the same place each time. Not to say it's a bad source, as apparently they're doing well where they're coming from, but rather whether there's something that's significantly different between the source system, and yours, that's causing a shock to that species.

My second thought is to try and get one with a gallon or more water from the source, and try to acclimate it to the new water over a period of 24-48 hours.