Were those highlights you created in the same paragraph? (Example: highlight the last word (uncapitalized) in a paragraph; then go back and highlight the first word (Capitalized) in that same paragraph)
Also, it would be better if exporting would include subheadings too, or make it an option. Currently in the local viewer, it seems to only include the topmost headings and ignore the subheadings. Like this:
## Part I heading (included)
text
### Chapter 1 subheading (ignored)
### Chapter 2 subheading (ignored)
## Part II heading (included)
text
### Chapter 3 subheading (ignored)
### Chapter 4 subheading (ignored)
|