What kind of lighting do you have? New frags? Is the chalice on the sandbed?
I've lost my fair share of chalices to tissue recession on the sandbed for reasons unknown. I like to get them mounted fairly quickly.
Not sure if it is causing your problem, but your alkalinity & calcium are a little unbalanced. I did better with chalices when I moved my alk down closer to under 8 dKH, closer to natural seawater.
Your acans look deflated, not receding from what I can see in your photo. That's often to high a light intensity. Good luck.