Running xournal 0.4.7 installed from repositories on linux mint 15.
Annotation works nicely up to beginning of page 684, where it suddenly stops at a horizontal line. I have some 1100 more pages to go on my doc :D
Suspect nothing wrong with the original PDF (downloadable on http://assets.jw.org/assets/a/nwt/nwt_E/nwt_E.pdf), since all the other pages are annotatable.
Tried annotating with different tools, all stop at the same point.