@LB In my environment, after opening one OneNote file which is stored in a library, I could add a notebook via the "Add notebook" option.
Or, add a new OneNote page for the existing OneNote file via "New Page".
Also, when other users add/edit the same file, the change will be saved to my side automatically.
For your issue, could you please confirm the following information about your issue?
- What did you mean by "I cannot add a notebook"? When you add a notebook, is there an error displaying? If yes, please provide the details.
- What did you mean by "I can't see when co-workers add information"? When you open the file, is there any error or warning displaying? If yes, please also provide the details.
- Please try to click "Sync" button at the top right of the page to sync the change when others add information.
Please check the above, and let's know the result.
If I misunderstand your meaning, please feel free to reply.
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