Where ARE OneNote files saved?

Today I was using OneNote to save some notes form an online course I'm going through. I realized that I was putting all these notes into the wrong OneNote notebook. I searched to see if I had a different OneNote notebook for the new that I wanted to create. There was none, so I proceeded to create it.

Only OneNote than complained to me, saying that a OneNote notebook by that name, already existed. 

Oh yeah, well then where in heck is it? I looked in my OneDrive for it (I have a Microsoft 365 Family Edition license). According to this web page all OneNote files end with a file extension that looks like this

.one*

So, I looked at the root level of my OneDrive for all files ending in .one*. It didn't find anything.

Huh?

The mystery is getting larger. When I look inside OneNote, to say add a new notebook, it will show me the names of the available OneNote notebook. But when I try to find them searching using OneDrive - no way. Nothing exists anywhere. I'm pretty sure that OneNote does use OneDrive for saving OneNote notebooks. I'm sure of this because when I use my Windows 10 desktop, or Window 10 laptop, or my Android phone, I can find all of those notebooks as notebooks I could add. So, what in heck is going on here? Does OneNote obfuscate the file name for some reason of it's own?