Posting this in reply to a previous comment I posted on this thread.
I tried a number of options posted online including:
- Making sure everything was up to date (One Note & IOS)
- Closing opened Notebooks (This proved to be painful as to do this I was trying to cut and paste less-used sections from my one active Notebook into a new Notebook which I could then close. This meant the new Notebook was trying to Sync and boosting up the memory usage in the process, crashing the app and the computer etc.... I eventually succumbed to taking my computer offline and closing the workbook manually, risking losing the sections I was moving across to the new Notebook which hadn't finished syncing... I figured I had backups anyway. I don't think I actually lost much, most of it had managed to Sync to OneNote online).
- Clearing Cache from the 'hidden' library files
But these didn't help.
Finally, I made sure I had my backups saved outside the application folders, then followed Microsofts steps to completely remove OneNote, reinstalled it, re-signed in, and so far the issue has been resolved.... I've been able to add PDF printouts to new pages and these have sync'd ok. There is a spike in memory usage when syncing up to about 5GB but it seems to come back down quickly... I'd suggest if you're having the same issue, try completely uninstalling OneNote - make sure you've moved your backup files out of the default location to somewhere else where you won't accidentally delete them in the uninstall!