eller:In the video track list, to the
left of the track view on the timeline there is a symbol of a blue
circle with a diagonal line though it. It mutes playback of the the
track, which, in the case of a video track, of course, makes it
invisible!
Funkar?Check that the "Split Screen View" icon (looks like a light/dark circle
at the top left of the Preview screen) is set to "FX Bypassed" and not
one of the other modes.