I've just been working on a project which had a mask set to animate onto a video clip. It was working fine for a bunch of other compositions which had exactly the same layout, but different information showing up on screen. For one particular composition it would preview exactly how I wanted it, however when I came to render it kept leaving out the masks.
I've noticed this problem before but managed to find a crude work around. Got a feeling I may hit this problem again soon so wanted to see if anyone else had experienced the same, and if there's any advice as to why it may be happening?
It could be AE's well-documented trouble with the Yosemite OS.
It could be H.264 or similarly highly-compressed video giving AE fits.
It could be operator error... unlikely with such a simple task, but possible.
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