Operating system: Windows 10
Graphics card: Nvidia GTX 1070
2.80, a7c5f4f2D657, blender2.8, 2018-12-28
Animated masks will appear animated when scrubbing through the timeline in the movie clip editor. When compositing the masks will still animate with the scene (regardless of being viewed through the compositing node or viewer node) however, when rendered the masks are not animated.
The blender 2.8 file can be opened in blender 2.79 and rendered and all masks animate as they should.
Exact steps for others to reproduce the error
go to movie clip editor
choose image or clip
add any number of masks to the scene
go to compositor
add an image or movie node based on your original selection
add a mask node and a mix node
merge the two with an "add" operation for the mix node
Thanks for all the work you guys do! You are the heroes!!!!!