The quest log doesn't say anything, its got all the ticks as if I completed it, even for "Check Logan" but nothing new. The witch has nothing to talk about. And if I check on logan it just gives me the same thing that he hasn't changed since giving him the cure and to talk to the witch.
After giving the antilycan to Logan, you need to wait a few days for the cure to work. Afterwards you check on him again and there will be a scene where you discover that the cure isn't working. It's only when you get that scene, can you then visit the Night witch to progress.