I want to make sure this isn't a graphics problem unique to my system before reporting to CW. Steps to reproduce:
 
1. Open a step sequencer track to reveal the controllers.
2. From the Controller drop-down menu, choose Velocity, Time Offset, or Step Play Probability.
3. Draw a curve. Upon releasing the mouse button, the curve disappears.
 
With MIDI controllers (Pan, Pitch Bend, etc.) the curve does not disappear.

Here is what i get with velocity

 
edit: replaced with new image of velocity

I could not reproduce the behavior you outlined following the steps given. I must admit I never use the step sequencer though. But since I read this thread and went and tried to reproduce the issue I have found the Step Play Probability controller. Wow. I can use this. This is a very nice controller.

scook, that's what I was hoping to get but I'm not seeing it.
 
I'm going to restart my computer and try again. If it works, I'll delete the thread.

One thing I noticed when creating an earlier video is the black on dark background drop down in my custom themes. I have a kind of a fix for it which will be added soon.

It was pilot error. There were no notes in the row I'd chosen to modify. I probably shouldn't be surprised that it's not possible to adjust velocity for a note that doesn't exist 
 
As I've said before...the main update this forum needs is a [facepalm] icon!

All this says to me is if Graig can be baffled than its not so surprising that I am always baffled!  Also I really like it when a bug is a non bug! 

It's pretty embarrassing, actually. To think I even started a thread about it...my only excuse is...well, I don't have an excuse. I guess I could try non compos mentis.

Anderton
It's pretty embarrassing, actually. To think I even started a thread about it...my only excuse is...well, I don't have an excuse. I guess I could try non compos mentis.

LOL and very funny. I know you knew about velocity and having a note in order to access velocity. But even something we know very well and can explain it to anyone doesn't mean we are not subject to brain farts from time to time. I sure am. I believe I am older than you and consequently I have a much longer history of brain farts. Its life. It just makes you human. You have not lost your guru status in the slightest. That is a fact. 
 
Now we forget about this forever! Which is easy for me at my age. LOL

Well, in your defense, you DID ask it as a question, rather than stating the situation as fact, so you got THAT going for you......
 
I once spent 20 minutes trying to jimmy the driver door lock, after accidentally locking the keys in the car while it was running, right outside my high school with all my friends standing around laughing at me.  It was only AFTER I finally got it open with a coat hanger that I realized that the whole time the passenger window had been WIDE OPEN.  (Of course nobody mentioned it, they took great delight in my not knowing, waiting for that AHA moment).  DOH!!!!!
 
Bob Bone