Grid list snaps back at least one row when vertical scrolling to bottom

[jonswaino]

I've spent quite a long time trying to diagnose a problem with the grid when there are more items than can be displayed in the list and the vertical scroll becomes active.

If I scroll to the bottom of the grid, it then snaps back up at least 1 row.

Have you any idea what might be causing this? I've even tried debugging into the framework code to see if there is something that might be causing it. I thought maybe the underlying list wasn't taking into account that it had a header so when scrolling it was assuming that it has more vertical space to scroll to. But I don't know what bit of code causes the scroll to snap/bounce back? I've tried using a vanilla list instead of the grid and it seems to work correctly, so I'm really stumped as to the problem and a possible fix.