I’ve tried that (I’m keeping it off anyway) to no avail. It doesn’t happen every time, but the areas in which the video cut out happens don’t switch. It’s only in transition areas between levels or between parts of a level, just not every time those conditions are met. I assume this isn’t something just Super Mario Bros. related though, because I really doubt that game is skipped over by enough people on this forum to have not had this happen to them. So I’m assuming it’s something about the way the OSSC handles the NES. I’ve tried changing LPF settings, but those are not affecting this.
It’s just enough of a signal cutout to force my TV to reconnect to the OSSC too, so it’s pretty hard to ignore. It’s short enough that the OSSC isn’t changing its light to red during that split second or displaying different information.