I have recently bought a devil's ivy plant. I have put it out on our balcony where it gets about 4 hours of sun a day. I have noticed that there are grey marks on the back of the leaves and in a couple cases they are on the front as well. I have only had it about a week and a half and watered it when it arrived. I have checked the soil and it doesn't need to be watered again.
I have another devil's ivy plant about 2 meters away from this one and it's thriving.
Has anyone seen this before?