I cannot export highlights from Apple Book on iOS13 I try to export highlights from a book purchased in Apple Book but when I select all my highlights, the “Share” button is still gray (so it cannot be clickable).
When I try with other ePub file this method works. Can someone explain me that behaviour and a work around?
The desktop (Mac) Books app still worked for such a book (bought in Apple Store).

Cmd+4 opens the notes section,
Open each of the different chapters in the notes section,
Select all using Cmd+A,
Right click on an empty space in the notes section,
Hit export and send to Mail.