Strange bleaching on ORA Blue Milli

[A.VOID]

I've had those ORA Blue Milli for a couple years now. Despite it being ridiculously slow growing, it has weathered every inbalance, power outage, nitrate spike, etc. It's also been through 3 different light setups and a tank move.

The thing has been rock solid for color and P/E for throughout it all.
Recently, I added a clear mesh screen to stop jumpers. It doesn't seem to have any effect on any other SPS. Good coloring, etc.
The Blue Milli has suddenly lost about half its color. Not completely bleached, but it went to a pale blue. P/E also appears to be 50%. Its in the same spot, water parameters are spot on and no other SPS show similar signs.

Any thoughts?

 

[sbin]

The mesh might be reducing PAR.

 

[A.VOID]

I'm sure the mesh is reducing some of the par, but i have no other SPS showing these signs.
Plus, I had this piece when I had lower lighting ... so the lighting doesn't seem to be the issue.

 

[LifeAquatic]

I dont think the mesh would be an issue. Have you added any recent additions to the tank? Nothing else has changed? If new corals were added I would check for pest.

 

[LifeAquatic]

Srry, noticed you said Mili and not Acro. Not sure what pest would be getting to the mili.