That's not quite the same: again, from memory, toggling the audio engine flushes buffers; pressing space (start/stop) doesn't necessarily and/or might just load the buffers with *new* audio data...

So the bromance is off?

KPerry
I actually had this happen years ago and serendipitously ended up with an amazing delay effect at the start of a track that stayed in the final version...

You are not alone; below is a similar post from a long thread about this issue that dates back to X1:
 
http://forum.cakewalk.com/FindPost/2385959
 
In my recent experience, there are cases where a buffered tail will play back at the start after rewinding (e.g. Clip FX tails), but for whatever reason, I haven't had a problem with them being printed to a bounce for a long time - maybe because it's plugin-specific. Per this old thread, the Sonitus DX FX are prone to this.

John
I normally slip edit it out. 

To elaborate on this, presumably you do listen to a project right to the end, so it should be obvious which track (or tracks) have any tail sounding after the project stops, so it should be a piece of cake to identify the longest one and slip edit the length of it accommodate the tail.
Ergo when you select all (or none ) the tail will be included with any bounce/export.

No this is not what I would call a tail. Its an unflushed buffer that will hold over to the beginning of a new track. Its a blip on the track. 

Ok, I thought that was what we were talking about.
 
Too late here - need sleep. Catch you in 10 hours or so

You can select a region longer than a midi clip. The bounced audio will be as long as the selection. Even a hundred measures longer (just did it). Besides, the answer to the OP is to use the new synth record option. Folks asked for this and I could never understand why they didn't just freeze. Mr. Copper's problem seems to be what this new feature is all about.

Why not use the new synth record option?   Mainly, I select groups of tracks by musical material, not by which VST is involved; also I'm still on the H rev and so far am afraid to change in the middle of this big project. 

I understand and agree. For every upgrade Twelve Tone or Cakewalk has ever released since "Pro Audio" my biggest problems have been trying to work on old projects in the new software.
 That being said; the way you have described your workflow, I believe you would benefit from K. As opposed to "freeze" record synth doesn't disable the VST. You can solo the specific group of tracks you want to create an audio clip of, select a region and punch record that part. Then move the resulting clip to a new track and record another group of tracks.
 I'm not trying to sell Kingston to you. You've paid for it already. I do believe however, you will ultimately be more satisfied with K than H. I am.