I would say, random after shooting, but never disturbing /DCIM/*.*.
It's normal for the viewport to show random stuff during or immediately after shooting, in any mode. The viewport memory is used for other stuff. What I'm trying to understand is if you see the problem while the camera is just sitting, showing live view.
next build... misunderstood...
Again, no idea what you are trying to say or what the screenshot is supposed to show. I see a corrupted live view on one side, but without an explanation, it doesn't mean anything to me. If you want to communicate, please use words.