Delete a scene or timeline clip AND close the time it held. scope "all_tracks" (the default) removes that span of time from every lane, so everything after it moves earlier together and stays in sync; clips and captions over the span go with it, and one that crosses its edge is split or shortened. scope "own_track" closes the gap on the element's own lane only (for a scene, the other tracks then drift by its length). delete_element and delete_elements leave a clip's gap open instead. Refuses, naming the fix: an unknown id, a sticker or caption (no lane time to close), a locked track the edit moves, or with all_tracks a clip that runs past the main track's end.