Here’s a list of things you can do to troubleshoot hyperlinks not working in OneNote:

1. Check the link URL for typos or incorrect characters, such as spaces or slashes.
2. Try copy and pasting the link into your browser to make sure it works.
3. Try using a different web browser or internet connection.
4. Check your OneNote Settings for any restrictions or permissions set for external links.
5. If you are using a browser extension with OneNote, such as LastPass, try disabling the plugins, and then check if the hyperlinks begin working.