I thought I read that she got a 3-week or so extension on that, due to she had been “sick”. ??
http://twitchy.com/brettt-3136/2016/09/17/hillary-finds-time-for-tonight-show-taping-needs-two-extra-weeks-to-answer-25-questions-under-oath/
Here is a link about the extension. Sorry if the source is not the best, (very busy here), but seems to support the delay.