Sunset montipora white flesh exposed

[ineption]

Dear forum members,
Having a issue with my Sunset montiporas which are showing exposed flesh which is quiet worrying. All the rest of the corals are fine including my acropora
All parameters are fine
Salinity 1.026
Cal 460
Dkh 8.1
Mag 1380
Phoshpate close to 0
Nitrate close to 0
PAr is 150 next to monties
I have attached pictures as can be seen it's the peak top bit. The polips are still out & stay that way, but the white flesh is visible.
Any help would be greatly appreciated.
Thanks

 

[Backreefing]

Sunset montipora? It doesn’t look like sunset , could be the light. Maybe it browned out on you .
Time and high flow is all you can do .

 

[ineption]

Sunset montipora? It doesn’t look like sunset , could be the light. Maybe it browned out on you .
Time and high flow is all you can do .

Yeah all it's a poor picture, due to blues. I thought it could be the light, but 150 par isn't that much, although I had at 1 point had the whites turned up, so maybe that caused it.
I was hoping someone who has seen a similar problem could share there experience.
Thanks for replying