I've reviewed the cache and the story chapter pages just aren't in it.
As far as I can tell, FFF is reading the cache correctly. I can't tell you why the chapter pages aren't there.
What is there is also quite odd--there are a bunch of calls ostensibly from pages sourced from fanfiction.net to https://127.0.0.1:54553. I'm baffled what that would mean, but it suggests a proxy or possibly something nefarious...
I don't think there's anything sensitive in the list of cached pages, but I'm curious if anyone else recognizes anything in the list: