So I'm having a problem in AE using auto trace. I used Creative Cows super tight junk matte to the T and it worked the first time with a female facing the camera talking, 8s clip. I then moved on to a gentlemen doing the same, 10s clip, and used the exact same setting only to the a problem of the auto tracing not fully tracing the gentlemen. The first frame has a full trace but as I move to any other frame is has the right side of the screen "cut". You can see in the picture below what I'm talking about. Any ideas?
Any block artifacts in there? Did you reposition the layer? Could simply be a problem with teh content being so near the edges which may prevent some internal operation of the trace algorithm (buffer expansion and smoothing, more specifically). Could also be, that you simply exceed the number of points per mask. It looks pretty dense already. I would try this with more loose settings and possibly pre-compose the contour, moving it more toward the middle.
So, I've shrunk the size down so the person is dead center and smaller and still same problem. What's weird is that it's even tracing things that are "off the screen". I'm really not sure what's going on.