Hello Pressbooks community. Well I’m currently developing a plugin that uses custom fields in the Chapter CPT of Pressbooks. The problem comes when ever i export/import the book data. When i try import it in a clean site install using just Pressbooks and my plugin, i don’t get the data to show in my custom fields. If someone knows what might be the problem or if you have any clue i would be very happy to hear from you.
BTW i added custom fields in the Book Info section of Pressbooks and this data seems to export and import as expected.
All the above were tested on:
Pressbooks 3.9.9 and 3.9.10
This is the way i use to add metaboxes and metafields: