Have assembled many clips into time line, but forgot one. Moved playhead to location between 2 clips. Right clicking shows split grayed out. Edit and icon for split also gray. Tried selecting all clips to the right - didn't help.
If the playhead is between two clips, there is no surprise that split is disabled. Split only works when the playhead is on a specific media clip. Typically videos. So try placing the playhead somewhere between the beginning and end of a clip and split should then become available.
Perhaps think of it like this. Imagine split to be like a big blade slamming down on the timeline. And further, imagine each video clip to be like a sandwich on the timeline. If the timeline has several sandwiches lined up but the playhead is between two, there isn't a sandwich to split.
I dunno why. Perhaps because we all eat. I love food analogies.