The issue below seems to be article-specific (i.e. it manifests itself for this specific article, but not for all articles from Medium).
Original article: https://medium.freecodecamp.org/why-most-redesigns-fail-6ecaaf1b584e
This is how Lexper parses it: https://lexper.com/demo?api=extract&url=https%3A%2F%2Fmedium.freecodecamp.org%2Fwhy-most-redesigns-fail-6ecaaf1b584e&js=0&media=0&feeds=0
If you compare the links above, you'll see that the Lexper's version of article starts with the text: 'The primary area to click for viewing the story was also shrunk in the redesign...', while in the original article this paragraph is far from the beginning, and all of the paragraphs before it seem to be omitted by Lexper.