Blastomussa receding tissue

[Reef_Geek]

One of my Blastomussa started showing receding tissue and exposing skeleton today. This is the second Blastomussa I've had issues with this year. Last time this happened... had a nice 5-6 head colony that looked great for a week with good polyp opening and colour, eating frozen brine shrimp, and then it just started to expose skeleton and its tissue fell off the skeleton. That one died. I thought I killed it by putting it too close to the light off the start. My next two specimens, I placed deeper in the tank. About 8 days ago, I consolidated my two smaller reefs and put everything into a larger tank. I thought my Blastomussa had adjusted, but one of the pieces I overlooked and again placed too close to the top of the tank. Now it looks like this...



Finally, now doing some web searching. I just read that Blastomussa are actually surprising tricky... having very latent reaction to stress, and typically thought to be due to being exposed to bright light too quickly.
Reference link
It's been 8 days since I moved my 2 tanks into one big reef, and it was showing good health, eating brine shrimp, and good colour. But 8 days later it's showing stress. Bugger. I've just moved it to the sand bed, might be too late. Good thing my other big colony is in a dimmer spot and I didn't get too ambitious moving it into the limelight.

Anyone else with similar experiences with Blastomussa?