I suspected that it could be something related to the cache and thought by cleaning it up and re-downloading the notebook from my OneDrive it will rebuild the index just for OneNote to solve the problem. What ended up fixing mine is quite simple. It’s also a time-consuming process and could take hours to finish the whole thing. It may work in your case but not in mine. I tried to rebuild the search index in Indexing Options from Control Panel, by going to Advanced options and click Rebuild button. But after a few releases without seeing it being fixed, I realized it must be something else. I first thought it might be the new Windows 10 inside build that breaks the search index on my computer and that should get fixed at next release. But lately, the search feature hasn’t been working to its full capacity, always ending up nothing for the keywords I know existed in the notes I took. I have a lot of notes in a couple of notebooks in the app so I heavily rely on its search feature to find what I am looking for. OneNote is my go-to tool for notes taking.
