“Copy to Books” iOS13 solved
Noticed that the copy to books option was missing in iOS13.
https://discussions.apple.com/thread/250749797
Work-around would be to click share -> open in books -> (once the pdf is open in books) click share again -> click “copy to books” which should now be available.
After this you should find your pdf in the Books library
Hope this works!
iPad mini 5 Wi-Fi