Eric, what about the dirty screen reason you proposed? I have noticed that after i clean the screen carefully, touch seems to work fine. Could that be the key? A touch screen which is much more "sensitive" to dirt. Did you clean the screen before bringing it to the store?
I purposely did not clean the screen before I brought it into the Apple store, but as luck would have it, the iPad just decided to not have any issues for that 20 minute period while I was there.
The issue is definitely temporarily cured by cleaning the screen, but over time I was finding the need to clean the screen more and more often, and that should not be necessary.
I’ve been using the iPad since Tuesday and have purposely not cleaned the screen, and since restoring from my iCloud backup, the issue has not appeared again. So maybe the issue is a combination of both software and hardware. It’s hard to know for sure. We have reached a point where software and hardware are so connected that it’s possible for an issue to be a combination of both.
I’m just theorizing here, but perhaps if two particular kinds of apps are running at the same time, then the screen becomes more sentsitive to being dirty and the problem appears. Since everyone uses the different apps, the issue only appears for a small percentage of users. Or maybe the issue is caused by installing two particular kinds of apps on the same iPad in a certain sequence, or while a certain other app is running in the background, but then restoring from a backup fixes the issue as everything is reinstalled in the “proper” order.
I’m just theorizing here, but it could be something weird like that which is causing the issue, and if so it will remain a mystery as to what exactly is causing it, but maybe a fix can be figured out anyway.