Recently upgraded from Ubuntu 16.04.6 to 18.04.4
This package also updated LO from 5.1.6.2 to 6.0.7.3
NOW, NONE of the videos in my Impress presentations will play without a constant lightning bolt flicker across the screen. These are MP4 files and they played beautifully on LO 5. I have experimented with other file types but no success.
Further, I have upgraded both my desktop and laptop with exactly the same results!
WHAT AM I MISSING HERE?
This update also upgraded many libraries, among which GTK+ and OpenGL. What happens if you disable OpenGL rendering?