Question: PP changing the points on my Opacity Mask Path

[Niki@WSU]

I have a video clip of a penguin and I need the background removed. Unfortunately, I can't use the Color Key effect because the penguin is white and the background is white snow. So, I decided to put an Opacity Mask Path around her frame by frame. After spending several hours adjusting the points as close around the penguin as possible and adjusting the feather, when I hit play, PP didn't keep all my mask adjustments and created a sloppy version of the mask that cuts the penguin off as she walks. Why did this happen? Oh, and as I was adjusting the mask, PP crashed several times.

[Ann Bens]

Did you add or deleted nodes during masking frame by frame?

That could explain the behavior of the mask.