User can't update story

One user is complaining she can't update her story, she can add a new chapter and there are no problems or errors when submitting it, however the new chapter is not added to her story. She's the only one having this problem or at least the only one who has reported it.
I tried to add a chapter myself to her story, I get a success message but the story is not updated. HOWEVER I can see the new chapter listed when I click on edit and go to the bottom of the page (where you can add, delete, edit or change the order of the chapters).
The "last updated" date is not changing and the chapter doesn't show in the chapters list... I find this really weird. Anyone have an idea?

Thanks