Sidenote from experience: If you move this coral or touch it with forceps, etc. sterilize or wash utensils even if no visible mucus or film is there. I have inadvertently lost one from such a "cross contamination" even when this coral is not in aggressive behavior mode.
If you ever are in a desperate situation with these corals and one side seems to be injured/tissue rotting there is a method I was successful with:
The coral was rescued from a local shop that I no longer visit. The coral's tissue was rapidly rotting but one side still had blisters expanding.
1. Immediately work to maintain your pH at 8.4 at least. Best method is kalkwasser auto topoff with Tunze (super concentrated) and macroalgae on alternate light timer in refugium. if that doesn't get you to 8.4 use two part dosing. I use Seachem Reef Fusion with success.
2. Find a low/no flow, semi secluded spot in the tank with sand bed. This area must be shaded, only receiving ambient light from non shaded sand.
3. Gently place the sick/injured coral in this spot and carefully bury the animal to the point where only the healthy or semi healthy tissue is exposed.
Leave the animal completely 100 percent undisturbed for several weeks. Do not attempt to dip the coral or irritate it. These measures only make the condition worse. Water test consistently and treat with Strontium and Iodate (I use Lugol's Solution). Make sure you keep pH at 8.4 and watch water parameters closely. I would leave the animal there until all visible tissue is healthy and there is no sign of the decayed flesh. When you think it looks ok to move back to another area, give it a few more weeks, then slowly transition to a low light low flow area.