Plates not showing PE during the day anymore

[TWT5011]

I have 3 small plates, no large than 2" each... all three beautiful and were were extending their polyps during the day for about a month... they all three moved around some in a small area of the tank... often times touching, inflating, climbing on each other... now they no longer show any PE during the day... and generally showing show PE during the night. I'm bummed... I love the plates but with the PE... any ideas? Maybe I should move them apart? BTW... all of my other corals are happy and params are inline.

 

[Tahoe61]

What type of plates are they? The typical Fungia sometimes does not show expansion during the day, the Heliofungia should show polps. You can try feeding them during the day. Drop a couple pellets on the top of each.