Illustrator Blend Problem

I created a simple Blend tutorial a few years ago and was sharing it with my group recently and now it doesn't work. The basic operation was to create an ellipse, use the scissors tool to cut the top and bottom anchor points which creates two ellipses. Then use the blend tool to blend them together. As you can see in the attached image, the blend now tries to blend to the center because the scissor tool reverses the path on one side. The easy fix was to reflect one side horizontally, but it wasn't obvious and first and totally unexpected.

When did this change and why?