I can't reproduce it on my PC running Windows 10 (the letters are always at the top of the list for me), but I don't doubt you are seeing it, as I've seen different behavior on different devices for Windows 10. I'm utilizing what Microsoft gives me, so I'm not sure how much more I can improve it. When I call into Microsoft's library, I indicate that I want the entry scrolled to the top of the list. That's about all the control I have over it. Trying to manually calculate the amount to scroll and scroll it myself is incredibly problematic with Microsoft's UI design.
Mike
Mike