This is an older post, but it came up at the top of google for me, so I just wanted to link a solution that wasn’t listed here, but worked for me with my horizontal scroll box!
Essentially all you have to do is set your scroll box’s render transform scale to “-1” on your preferred axis. Then put all of the items that are in your scroll box into either a Horizontal, or Vertical box based on your axis, and now set the scale to “-1” on the box you chose. Make sure it’s in the same axis as your scroll box!
Good luck, and hopefully this helps! 