Last modified: 2013-11-20 15:23:46 UTC
In statements, the property label on the left updates its vertical position when the user scrolls to far down, in order to keep the label visible. If after the user scrolls down enough that the property gets moved downward, the user scrolls back up fast enough that the top of the statement group is never within a certain small distance of the top of the screen (say, by using page up), then the vertical position will not update.
https://gerrit.wikimedia.org/r/#/c/85208/