Book and quill placed into lectern deletes pages and censors numbers

When placing a book and quill with multiple pages into a lectern, random pages will be deleted and occasionally random numbers (coordinates) will be replaced with pound signs.

To reproduce the issue, I continued writing in the same book and placed it back into the lectern, this time instead of deleting page two after writing in page three, it deleted page three after writing in page two. It also replaced coordinates on the first page with pound signs.

Expected result is to be able to place the book and quill into the lectern with no changes in the writing on the pages.

Actual result is the lectern randomly causing pages to delete, and censoring unnecessary characters.

UPDATE: It occurred again while just holding the book in my inventory. Wrote in page 2 a series of coordinates, threw it to another player, and page two was deleted. The book and quill has been renamed in an anvil - maybe affecting something?