@azslow3: Ah! I always make a copy somewhere else, then drag back into position.
"Lock Data" makes repositioning unnecessary. Thank you!
 
@stevec: That just gives me a cropped copy of the original clip.
When I stretch it to hear the full length of the note, the other 2 notes appear.
 
But these are workarounds for what are everyday housekeeping tasks.
 
To unleash the full power of clips, let the user decide when to use one.
And by implication, free notes from the obligation of being in a clip.

@stevec: What you have revealed is that splitting midi clips does not divide the notes into two clips, as one might intuitively suppose. Both clips still contain all notes.
 
So if the user later manually adds a note nearby and Sonar extends the clip to fit the new note, old notes assumed to have been removed by splitting suddenly reappear.
 
To be safe it's best to copy a clip, remove unwanted notes from both clips, and only then resize as required.