In AE CC 2017, I found a very strange behavior when using Shift+Parenting. To recreate this, place two shapes in a new comp, one with 2 keyframes to move from top of screen to bottom of screen, the other starts out at 100% scale and shrinks to 20% scale. Now, If you Shift+Parent the shape that changes scale to the shape that moves when the first shape is at 100% scale, everything works fine. But if you shift+parent the one that changes scale when it is at 20% scale, things go wacky. It changes the settings of the scale animation, so instead of 100 to 20, it becomes 500 to 100. What is going on?
Shift parenting matches the position scale and rotation property of the Parent layer at the current position of the CTI.
Move the CTI to the first frame of the timeline and Shift Parent and you'll get a different result than you would if you moved the CTI to the last keyframe and did the shift parent. It's always been that way. I don't think it's a bug.
OK, thanks for the reply. Maybe I need to suggest another form of parenting that doesn't change what traits the child starts with, just add the traits that the parent has. That's what I thought it was, but apparently not.