White tips is when they not extended/opened fully
New lights could be a problem, remember this coral doesn't need loads of light.
The tips normally indicate an aggressive coral's attacks, I see it from my hammer coral every now and then
Lastly, it might be nothing you will ever work out, soft corals can some of the strangest corals. I have a pincushion that refuses to eject his polyps fully, yet he is still alive and growing ????
Give it a couple more days.
Any possible fish or crabs that could be nibbling on it ?
If it keeps getting worse, frag the branch, in case it is some sort of disease