Richard A shared these words of wisdom:

> Obviously, something is preventing the add-in from completing the
> print job, but I have no idea how to fix this. Help!

Dumb question:
Did you check the "Unfiled Notes" section?
Could it be that the missing results might be there?

Did you check the settings for where the results of "Print to OneNote"
ought to go?
(Tools | Options | Send to OneNote ... )

Rainald