Have an old background that I'm converting to HD and to eliminate some banding I added "Channel Blur", bluring the blue channel 24 pixels. Well for a few frames the lower corner of the video completely loses it's blue channel, leaving me with a bkg with a green square. After a few frames it goes back to normal. Happens a few times during the video
Background Blue Channel Only:
Just for giggles, I tried blurring the other channels and get the same problem.