Now, I know I can export to PNG sequence, but exporting to video with masks has never been a problem for me before this update and it should work. See video.
Found the work-around:
My mask was comprised of symbols. I needed to break them apart until vector shapes and fill them as a complete unified shape.
Recap: Avoid masks made up of various symbols. Flatten them into vectors.
Workarounds are great but we need better than workarounds.