Dear respected AB Ortega,
Good day! Thank you for posting to Microsoft Community. We are happy to help you.
I’m sorry you’re having a problem with but based on your description we can work together to resolve it.
For the situation you encountered, we deeply understand the inconvenience caused and apologize for it.
As per your description, it seems that the problem only happened with OneNote 365 app itself. However other Office 365 application, the "Share" function work well. Firstly, may I know if my understanding is correct?
Since you are using OneNote 365 desktop app, to check if this problem happened with a OneNote app itself, I suggest you go to OneNote Online, find the notebook and try to open the notebook into OneNote online app then click on "Share" button and verify the result with us.

Also, if the issue only happens in a specific notebook, you may create a new notebook, copy and paste all notes in the new created notebook to see if there is any difference.
We appreciate your understanding that sometimes the initial suggestions may not resolve the problem very soon. However, we can work together to narrow down and resolve the situation. So, please kindly provide more information below to let us work further.
1.Does the issue happens in all notebooks or just a specific notebook?
2.Can you recall when this behavior starts e.g., after Office update or Windows OS?
Appreciate your patience and understanding and thank you for your time and cooperation.
Sincerely,
Waqas Muhammad