Here is the option setting:
And here is the scrollbar in the treeview that I am not expecting to see:
Any advice or insight would be greatly appreciated, as always!
Regards,
-David
The Horizontal scrolling style options only change how horizontal (left/right) scrolling behaves in the tree, with options to mimic the way horizontal scrolling worked in File Explorer's tree in various versions of Windows.
The vertical (up/down) scrollbar is always visible (unless all the items fit on screen) and not affected by those options.