Following the above, I found out that Quick Notes only loads when it points at a section within a closed notebook. If you reopen that notebook Quick Notes gets stuck after syncing, as shown on Jeremy007's screen capture . To
workaround it, I moved the Quick Notes's section to a new Notebook and then I closed it. It works although I don't think this is the way it should work. I have tried both Office's quick repair and online repair but it doesn't make any difference. I wonder
what is causing this strange behaviour. It doesn't matter whether the notebooks are stored locally or in Onedrive so it's not a syncing problem. What about Registry?
Thank you this fixed it for me. What I did to get around the fact that OneNote won't sync a closed Notebook to Onedrive, was when I first created the new Notebook instead of selecting the "OneDrive" location I selected "Browse" then navigated to the OneDrive
folder on my PC and created the new notebook there. Now the notebook syncs through the OneDrive app instead of directly through OneNote. The end result is the same however, as long as you keep OneDrive running. Thanks again for the fix.