A family of Microsoft products that enable users to capture, organize, and reuse notes electronically.
Hi there!
Based on your description, I would agree that this issue happens after you deleted it. It could be that it hasn't fully synced yet and then you deleted it which causes the "Content not yet available" error. This error occurs when your OneNote notebook content isn't synced completely with the server, or when the client is offline or not properly authenticated.
On this case, what I suggest is to try to wait for your OneNote to sync properly. You can also right-click the notebook name > Click the Sync This Notebook Now. Leave OneNote open and idle for a few minutes afterward. Sometimes it just needs few hours to resolve the conflict.
Also, I suggest to try checking the OneNote Notebook recycle bin which you can find in the app itself. Go to History > Notebook Recycle Bin to see if the original page still exists. If it does, try to restore or permanently delete it.
I hope the information helps!