Maybe it is blocked due to another quest, which has to be done first? Any open quests, which can be done?
Sadly not: I've done all other open quests except "Behind The Door, Part 5", so unless Leah decides to show up, all I can do is re-check the stupid forest all day with the odd girl-teasing in-between to lighten up the boredom... I'm at 34% completed, by the way.
Any ideas, or should I go back a few saves and approach this quest while still having other open tasks?