Thank you, the bug is still an issue for me as well. Which Plattform are you experiencing this bug on? Because I have yet to see this happen on my Win 10 worlds. iOS only so far
Happened again
As far as i can see, this is intended behavior. Similar to crops that will pop off when the farmland dries out. Since coral fans don't have any drops like seeds, they will just disappear with no remains. But who knows i could be mistaken...
Were you able to take damage or drown in your case? If so then you aren't a duplicate and this is a legitimate new ticket, also for me the interface would at least partially become invisible or unusable and I tend to get a loading bar like in my gallery I shared here https://imgur.com/a/Qqcrt1A