I'm working in After Effects CC 2105
I have a shape layer with a rectangular path on it that has been converted to a bezier path.
When I animate this path
ie - bringing both of the left points in a little
Instead of animating correctly, the whole shape scales down to nothing then at the end of the action it jumps to how it should be.
Any ideas what is going wrong?
Probably Operator Error. You might have had some other property selected when you thought you were fooling with Position.
By default vertices animate in a straight line. I am guessing you either tried a rotation or you moved the points from one side to the other so that the shape does some odd things. Type "animating masks" in the search help field at the top right corner of AE and study up on the various options for animating masks or shape layers.
There could be a sneaky key frame hiding right next to your end key frame, which could explain the scaling then jumping...