Yes, I have this same problem on occasion. Happened again this morning. All of my orders defaulted to Priority Shipping, even though the customer choose First Class/Ground Advantage. When I click on first class to change it, the screen simply scrolls to the top as if I'm hitting the <pgup> button, just as you stated. So frustrating. My only resolution is to wait...come back...or I print each label through the seller app on my phone, which is ridiculously time consuming and annoying. Sorry I have no solution for you, just wanted you to know you are not alone. There doesn't seem to be a set time it happens. I've even restarted my PC to see if it would reset somehow. Then, it just magically goes away after a while. But does resurface at times.
