Split MIDI Clip Bug (SPlat, 2017.06, 2017.07)

Sorry to say but that is a "feature"... not in "split" only and exists for long time (just checked with X3, but I guess it was there even before).
 
It is a property of MIDI Clip slip editing in combination with automatic MIDI clip extension.
 
1) Clips boundary changes in Sonar are not destructive, so the whole information is still there but a portion of it can be "not in use". That happens when slip editing or splitting and that is a good feature.
 
2) When you add notes in in PRV "not so far away" from existing clip (there was a long discussion before about 2 measures rule), Sonar automatically extend existing clip instead of creating new one. That is also a good feature.
 
But... (1)+(2) produce the effect you observe. When you modify existing note which is longer then current clip boundary, Sonar extends the clip. And not destructive splitting keeps original length of notes. Not nice.
 
So I completely agree that is not what people expect it that particular case, but a very good proposal is required to "fix" that without breaking (1) or (2). I mean imagine after splitting and deleting the right clip you have started to add notes to the left one... And you can not because its right boundary is "fixed". Ore imaging you can no longer slip edit the clip after splitting.
 
The "workaround", and that make sense for me: if you want permanently split the clip, "bounce" it after splitting.