When we use the <!--nextpage--> shortcode in our posts to have multi-page posts, the pagination links do not work in preview mode. They do work when the post is published though.
In preview mode the links go to the root domain url with the "/2/" at the end of that, dropping the post permalink info. Clicking on that makes WordPress then look for some other post with a 2 in it's permalink or title, instead of the 2nd page in the post.
If I disable the edit flow plugin, this issue goes away.