I’ve had a similar problem, which I’d assumed was because I’d usually forward the mail to OF, then archived the mail. So the Mail’s location is wrong. That’s just a guess.
But because of this, I usually forward the email to my OF Inbox address. This looses the link to the email but its contents are in the OF notes.
This works well for me because most of these emails include lots of distracting junk that I can delete and because I can add some notes about what I actually need to do with the email when I later pick it up.