Thanks for replying.
This is the first time it has happened, the user has several folders containing files (on their iPad), (some .pdf's with additional highlights) these files are typically company agm board packs so contain pages of text and photo's too.
I put it down the fact that when I checked the app store for updates there had recently been an update and the user had not rebooted their iPad for some time, hence some of the underlying adobe reader files were perhaps between versions.
I don't know how you handle files when performing an update, do you close the app, flush files from memory and do a clean update?
I can confirm that the .pdf file had not been sent as an email attachment after having added the highlights.
Because the acrobat document contains so many pictures (32 pages and 8.5MB) when scrolling through it takes several seconds for some pages to appear, and others with text and pictures quite a while for the text to become sharp, I presume this is because the Acrobat Reader cannot open the 8.5MB file in one go and has to keep swapping it out of memory. Having reached the end if I scroll back to the beginning it takes 10's of seconds before the first page re-appears, otherwise it's just a white page. Interestingly in iBooks the pages appear almost immediately when viewing.
The iPad in question is model MD368B/A, 64GB, Software Version 7.1.1 (11D201) and has 28GB Memory available. Usage tells me Adobe Reader is taking 328MB and is version 11.3.1
I have just finally browsed back to recent documents, opened 2 or 3 other documents and then this one again (from recent) and it is now broken, just shows white pages (and on the thumbnail too) with my test highlights. so I can now apparently reproduce it.
Hope this all helps you re-produce
Regards,