Hi,
I'm running Blender 2.80 (latest nightly build from 2019-07-05) on Windows 10 x64 with 64GB RAM and nVidia 1080 card.
There are problems with the drawing of masks in the Movie Clip Editor, they seem to jump around inconsistently.
This doesn't appear to happen consistently, but usually one out of two attempts would replicate this behavior.
# Start blender.
# Switch to the Movie Clip Editor.
# Load a video (in my case 1920x1080)
# Track some feature in the video.
# Switch to mask mode.
# Add a mask (in my case, a circular one using Shift+A)
# Shift click on the track to select them both.
# Press Ctrl+P to parent the mask to the track.
# *** At this point the mask would jump around. If it doesn't, delete the mask using X and try again from step 6)
# Scrubbing would cause the mask to jump back in place.
# Trying Ctrl+Z would cause the mask to jump to the wrong place again.
It makes it very hard to tell whether I'm masking and correctly since the mask appears to jump around inconsistently in the view.
See this [[ https://drive.google.com/open?id=154YHlJoZuHj6bM8KEnl1MyAxDfcq52y2 | video ]] for a demonstration.
Also see this bug for related issues, I've re-opened it since it wasn't fully fixed (see the latest video demo there from Dec 29th).
https://developer.blender.org/T57646
Thanks,
-- TR