I have roto brushed several shots of a hand touching an iPad screen and am having an issue with the exported footage. It seems that the hands are rotoscoped properly in After Effects but upon inspection in the rendered quicktime movie there are glaring flaws in the movie. Please see the attached image. Does anyone know why this issue is occurring? I have tried exporting as Lossless as well as Apple Prores 422 HQ and the problem persists.
Either it's the ProRes Alpha bug striking again or, which IMO is more realistic to assume, the propagation actually has eroded areas you didn't want it to, you jsut don't notice it in your preview because you have a duplicate of the same layer underneath... and somehow you have something going on with other effects or layer styles that affect rendering order and in turn your Alpha... Something like that for sure. I'd definitely doublecheck your roto work against a uniformly colored BG and toggle the visibility orf other layers...
Did you freeze your Roto Brush before you rendered? I've seen this kind of thing happen when you don't.