I have the Synchronize Vertical Scrolling OFF/disabled when I see the problem behavior.
When I turn Synchronize Vertical Scrolling ON it gets weird.
If both views are at line 1 with my focus in the left view, and I then set Synchronize ON, then move the focus to the right view and scroll down to the end (2003) the left view follows along.
If I then move the focus back to the left view the cursor disappears and both views stay at the end. If I then press the down arrow once both views snap to line 2 and the cursor appears at line 2!
If I then move the focus back to the right view the cursor again disappears and both views stay at the top. If I then press the down arrow once both views snap to the bottom of the file and the cursor appears back at line 2003!
With sychronize ON each view seems to have its own memory of where you left it and it goes there when you move the focus dragging the other view along with it.
With synch OFF, the left view at line 100, the focus in the right view I can scroll the right view independently of the left. If I add a line in the right view at line 20 (above the position of the left view) the left view doesn’t move. If I add a line in the right view at line 120, (below the top of the left view), the line opens up in the left view. If I add a line in the right view at line 160, (below the bottom of the left view screen), the left view doesn’t move. But, if I move further down in the file in the right view and add a line at say 1800, the left view will snap down to show the added line.
The behavior is hightly inconsistent. Hmmmmmmmmm.