If HP Support Assistant has updated your Printer/Scanner and all of the available Scanner Drivers are installed, then I suppose you have to look to Paint.net for answers. I'm running WIN10 on an HP and have a HP Printer/Scanner like you; but, I don't have Paint.net.
I can tell you Microsoft Paint 3D, which comes with WIN10, doesn't scan from the app. OTOH, the original Microsoft Paint, that also comes with WIN10, does.
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