Hello,
 
So I know for a fact this is a Sonar issue, as I test this outside of Sonar and CC #38 works.

Here is my issue:
 
#1.  Load up a brand new project (not from a template)
#2.  Load up ANY VST, in this case I am using "Massive".
#3.  I can MIDI Learn any CC in Massive, #35, #36, #37 all work.
#4.  I try to control a parameter with #38 and nothing - HOWEVER, I know Sonar is seeing the MIDI data because when I turn the knob on CC #38 on my MIDI controller, the MIDI Activity in the meter bar on the track light up and show that it has incoming data being sent to it!
 
So I decide to close Sonar and load up Massive standalone, and guess what, CC #38 can map to the same parameter in Massive!

Somehow Sonar is intercepting CC#38 and not passing it to the VST.
 
Not sure how this happened or where I can even look.
 
Thank You,
Adam

to add:

CC#38 works fine for SONAR functions using remote control (pan, volume, etc...), it just won't pass CC #38 onto the VST

I do not have ACT setup.

Sonar is "intercepting" CC#38

I can confirm - just tried controlling a VST parameter with #38 and it wouldn't "learn" but would learn any other controllers I threw at it (although admittedly, I didn't try them all). I'll file a report.

Anderton
I can confirm - just tried controlling a VST parameter with #38 and it wouldn't "learn" but would learn any other controllers I threw at it (although admittedly, I didn't try them all). I'll file a report.

Thank you Anderton,  hey can you try CC #32?

I find the same problem there too!

add CC #66 as well 

Okay, I checked into it some more. CC#32 - 63 are the least significant bits for controllers with two bytes of precision. Controller #32 is used for the least significant bits of a Bank Select command. Aside from Bank Select, these double-byte controllers are pretty much not in use at the moment.
 
Another forum member pointed me toward an older post about Project 5 but it seems certain SONAR works the same, and it's very possible at least some other DAWs do too. Not sure what can be done about it, or why some LSB controllers are recognized but not others.

Oh interesting.  So is there a "safe" range I should set my controllers to?  I just got a Novation with 48 knobs/sliders, so I need a range of 48 safe CC's I can use.
 
Thanks!

As Craig noted, in the MIDI spec CC#38 is reserved (normally a prequalifier for a following command). It should therefore not be used as a single-byte controller, as it will be unreliable.
 
You just lucked out that Massive handled it in standalone, perhaps because Massive doesn't treat it as half of a 2-byte command sequence. Because CC#38 typically prefaces NRPNs, or follows CC#6 for advanced controls, there's no telling how any given synth or DAW would respond to it in isolation. I'm guessing SONAR assumes you're sending an NRPN, which it probably does pass on to Massive but the synth doesn't know what to do with it.

I usually choose my CCs from 20 through 31. There are other unassigned CCs, but this is an easy range to remember.
 

really helpful and thank you both Anderton and bitflipper.   Good information here.
 
This Novation unit comes with the dials set to CC #21 - 72...   so i figured I am good to go.  I will make sure to change those CCs to something else.  
 
Thanks for the assistance!!