Hello PaulRBlackburn,
Welcome to the Microsoft Community.
There is a real problem with the arrow keys in OneNote stopping working when using a physical keyboard and an Android device. This issue usually occurs after pressing Alt-Tab to switch apps. There is no permanent solution for this yet.
This is due to a compatibility bug between OneNote for Android and the physical keyboard, which is a technical support community that is not directly involved in the development process of Microsoft products, and I'm afraid that it can only be fixed by the OneNote team.
You can report this bug in OneNote by “sending feedback to Microsoft”. This will help speed up the resolution of the issue.
In the meantime, thank you very much for sharing with the community any alternatives you have found that work for you, as this may be of great help to users with similar issues.
Thank you for your feedback. I will also report the same issue in the OneNote app.
Best regards,
Ian - MSFT | Microsoft Community Support Specialist