Midi groove clips bug with the velocities?

I think that's working as intended. Groove clipping just copies whatever is in the original clip at the time you drag it out; the copies are not linked. This allows you to alter individual repetitions to add a little variety to the part. If you want linkage, copy the clip and paste as many repetitions as needed with Link to Original Clips checked.

I understand that; that's not the issue. The issue is the mixing of velocities, as described in numbers 5 & 6 in my original post.

 
Oops. Stopped reading carefully at the end there. Sorry about that. Yes, I can replicate that. Increasing the MIDI Prepare Using buffer under Preferences > MIDI > Playback and Recording resolved it, but I had to take it all the way up to 1000ms. I think this is an area that Cakewalk need to work on. There are way too many weird behaviors and resulting posts related to this setting.
 
But this is the first one I've ever seen that require me to set my buffer above 500ms.
 
 

I have kept my MPB at 250 for a long long time without issues.

 
I used 250 also for a long time without issues. Then I encountered a problem a few months back where I was losing part of a drum track on mixdown, although playback was fine. The magic number to cure that problem turned out to be 259. At that point I decided to give myself a safety factor and go back to the default of 500ms.
 
The whole concept is strange to me, and I've wished for a long time that Cakewalk would explain why it's needed, and exactly how it's implemented. Most synths can respond virtually instantaneously to real-time MIDI input, so I don't see why such a huge (in audio buffering terms) "MIDI" buffer is needed, and why you get these dropouts without it when, if I send the same data in as a real-time stream, everything plays fine.
 
I also wonder whether other DAWs do this, either explicitly, or maybe without revealing it or giving you control over the buffer size.

brundlefly

I have kept my MPB at 250 for a long long time without issues.

 
I used 250 also for a long time without issues. Then I encountered a problem a few months back where I was losing part of a drum track on mixdown, although playback was fine. The magic number to cure that problem turned out to be 259. At that point I decided to give myself a safety factor and go back to the default of 500ms.
 
The whole concept is strange to me, and I've wished for a long time that Cakewalk would explain why it's needed, and exactly how it's implemented. Most synths can respond virtually instantaneously to real-time MIDI input, so I don't see why such a huge (in audio buffering terms) "MIDI" buffer is needed, and why you get these dropouts without it when, if I send the same data in as a real-time stream, everything plays fine.
 
I also wonder whether other DAWs do this, either explicitly, or maybe without revealing it or giving you control over the buffer size.

Dave, I don't see other hosts even using such a thing as a prepare buffer, though that may simply mean they do it under the hood, so to speak.
 
Strangely, I've never had an issue that changing my MPB fixed.  Lowering helped me more than raising it.  But I always keep it in mind when other problems happen, as things can be interrelated.