my jumper ezbook3 pro has the same keyboard issue. It’s complete rubbish and will miss a lot of keystrokes when typing at a normal pace, or anything faster than very very slowly. I’m pretty sure it’s not a windows issue, for plugging in an external keyboard works like a charm.
I wonder if this is an issue with this model, or if I just got a faulty unit, but in any case, it’s a bit of a mispurchase.