Cursor location and other indicators within scrollbar is incorrect

I have a file that is 1301 lines long.

When I go to the top of the file, the scroll bar (on the right side) will move to the top.

When I click on a line within the displayed split, I see a black horizontal bar appear within the scroll bar indicating the relative location of the cursor within the display. Below is a picture of the black bar approximately in the middle of the scroll bar:

When I move to line 1227, line 1227 is in the middle of the split and I see the following. Notice that the black bar is outside the scroll bar. Since the line is in the middle of the split, I would expect the black bar to be in the middle of the scroll bar.

If I move the scroll bar to the bottom, line 1227 scrolls up and is approx 25% down from the top of the split (since the file end is line 1301). I think the correct behavior is that the black bar should be 25% down the scroll bar.

If I move the cursor to line 1228, the black bar disappears: