I don't know man, mine are definitely really active when lights are out, and a lot of people have reported theirs preferring to eat with lights out. Besides that, just about every species profile on the net describes them as nocturnal. I'm not saying that everything on the internet is true, but several reputable sources along with many keepers' experiences seem to suggest they're nocturnal.They are NOT NOCTURNAL, lol..... My polys sleep with the lights are offI think the misconception is that fish may go missing at night. It due them resting at the bottom when lights are off at night. That's when polys become opportunistic.
I've been snowed in today and have been down with my fish a lot, but haven't seen anything.If you have time sit and observe for awhile culprit may start up again.