Another chunk of my notes just disappeared. This time it was even more erratic than before (just random bits here and there being erased. One Note (at the very least the 2016 version on a SP3 running Windows 10) is completely unreliable right now. I hope Microsoft is aware of this huge issue.
One thing I would like to mention is that both times, the One Note application was running at half the screen size. I did the trick where you can kind of clip it to one side of the screen (in my case, the right half). Now, obviously this could have nothing to do with it but I thought it might be possible this could be the start of some kind of pattern.