Just in case this may help, I had same issue with my zoas as well. 1st week, all well. Second week started to close. By 3rd and 4th week, thought they were gonners. Moved them around trying different spots in tank, flow, lighting etc. LFS
told me to give them a lot of light and to keep in the top 1/3 of tank.
Breakthrough came when I couldn't find my colony at all. Turned out something had knocked them off of the rock they were on. They were wedged in rock work at bottom of tank and all opened up. I since have placed them in bottom 1/3 of tank and they are looking pretty good.
Maybe it might help, maybe not. Just thought I would share the findings.