Did you purchase this one in the sphag? or did you pot it later on? It looks like both have a case of rot. Is it mushy?
If it is, cut them off with a sterile blade and dust the wound with sulphur powder or cinnamon. Reduce watering so the moss can dry ontop before watering again. I find Phals do best in NZ in just bark or an 80% / 90% mix of Bark / Sphagnum moss.