2D light FreeForm: No interpolation between editing shapes?

I am trying to experiment with a 2D light/Freeform animating the shape of the light. Here are the steps that I am doing:

• I make a new 2D light freeform
• I go to animation window
• Hit Record
• click on frame one
• I edit the shape of the light (dragging point handles around) this results in an autokey (Giving me options for Local Bounds Center xy and Extent xy)
• I go to frame 20. I edit the shape of the light again to make a new shape. This also results in an autokey. (I can see Local Bounds Center and Extent getting updates as I drag point handles around for the shape).
  
• I scroll between animation frame 1, then back to 20. Nothing happens. The animation only retains what I last did on frame 20.
  
  What confuses me is that frames are autokeyed on any frame I pick and edit the light - but only retains my latest edit to the shape of the light. Unity does not want to remember how I edited the shape on frame one. It only retains memory of the latest shape I edit on any frame after that.
  

 

Just adding to the thread. I made a video, hope that illustrates this question better: