UWP: Why is the Icon Bar (Notebooks, Search, Recent Notes) Missing on the Left Side of OneNote?
Question:Why does the icon bar on the left side of my OneNote disappear? How do you get it back?
Answer:The interface of the older version of OneNote UWP does not have a button icon bar on the left.
The new OneNote UWP interface has this button icon bar. It can also be adjusted back with the old interface.
Solution:In the OneNote for Windows 10 options pane, find Navigation.
Turn off the switch for the Legacy Navigation Pane.
After you restart OneNote UWP, you'll be ready to switch back to the new version of the interface.
If you don't have this option, you'll need to upgrade OneNote UWP to the latest version.