The website does sync to the mobile app. But the mobile app doesn't sync to the website.
Most of my novels don't sync their chapters both ways, Swallowed Star being the only one I know that does.
This is annoying as if I click a book from the website, after having read a few chapters on my mobile, it messes up the chapters and I'll need to skim through the chapters to find where I was before. I.e website states chapter 55 while I've read to chapter 100. When I click on the book on the website, the book will sync the chapter to chapter 55 on my mobile as well.
It might not be a problem if its only 1 book, but when I have a large library filled with books, it gets really messy.
I've tried removing a book from library, then added it back. The mobile app will then ask me if I want to sync, I press yes. But its still only syncing from the website to the mobile app, but not the other way around.