Hi,
What version of OneNote are you using? Is it a desktop version?
Where are your notebooks stored? On OneDrive or SharePoint?
Have you tried syncing your notebook from OneNote Online? This can help determine if the problem is caused by the server or by OneNote.
In addition, if it's a desktop version of OneNote, please try starting OneNote with /safeboot switch and then clearing the notebook cache to see the result. To do this, press Windows key + R to open the Run command, type
onenote /safeboot and press Enter. In the opened dialog, click
Delete Notebook Cache button. Please note that this button will close all opened notebooks in your OneNote, but you can reopen them later.
Regards,
Steve Fan
TechNet Community Support