Sorry for the "dumb" question here, but, did you have a version of notion that "did" handle handwriting before?
If so, did you delete the install file(s) from your download folder?
Not meaning to insult your intelligence, but every time there's an upgrade or update, it downloads the install to your default download folder (windows, not sure if mac has this), and then installs it.
So if you had a version that worked, and you haven't cleaned out your download folder, then you "should" have have install file
I did see where you said you did a cross grade, but it wasn't clear whether or not you had a version that handled handwriting and lost that ability due to upgrades.