To resolve an intractable problem first isolate it to the correct box.
In this case there are 3 boxes: Pen, Surface, and Software.
You tried two pens, seems likely its not the Pen although I once encountered 3 pieces of equipment with the exact same problem.
You really need to try another Surface.
I didn't get a warm feeling form the earlier response about being the only one affected... that's not the same as tested and verified a pen works on another Surface with the same build. The devil is in the details.