According to the screenshot below, my MIDI track should be getting messages ONLY from my MPK225 Midi Controller on any channel (MIDI Omni). 

However, when I record my track, the softsynth Nithonat with "Enable MIDI Output" is somehow sending its MIDI out to my track! 

As you see here, I only should be getting MIDI from my MPK225.   

It is acting as if "All Inputs" is checked.  

This is a long time bug I feel.

I have seen this, but never got resolution to it. SONAR has no means to track MIDI events "at play" with the transport running, which has often become a thorn in my side. MidiOx is a program I have seen others mention, but I never spent the time to get it to work properly. For me, it seems that any track set to "Omni," regardless of source, is monitoring everything getting fired off (and there is no way to tell what tracks are sending what, sans a monitoring solution).
 
The only sure-fire way I have found to "resolve" this is to use channels; however, some VSTis fire off multiple channels with MIDI Output enabled. Geist 1 can discretely fire off 11 channels (not sure about Geist 2), so it reduces the number of inputs available for usage (and I hate adjusting MIDI controller channels manually to accommodate this). Channel 13 is the default output from my controller just because of one VSTi now.
 
It seems that MIDI Output on a VSTi simply puts all output up for monitoring by anything listening to the exposed channels (regardless if a specific source is specified), but not 100% sure on that.

mettelus
 
It seems that MIDI Output on a VSTi simply puts all output up for monitoring by anything listening to the exposed channels (regardless if a specific source is specified), but not 100% sure on that.

YES! that is what is happening!

How do you file an official bug report?  

Use the Cakewalk Problem Report Form.
 
Cheers
Eddie

I believe this is now only reproducible in environments that have only a single hardware MIDI input enabled. So if you have more than one USB keyboard or a USB keyboard and DIN port on an audio/MIDI interface, try enabling both in MIDI devices. Even adding the free LoopBE virtual MIDI port to your system might eliminate the issue since SONAR will see that as an external port driver being presented by the O/S.

Is it possible the MPK is receiving the soft synth midi output and the MPK is set to midi thru? 

filtersweep
Is it possible the MPK is receiving the soft synth midi output and the MPK is set to midi thru? 

but my MPK MIDI Input in Sonar is disabled, unless I am not understanding.

I filed a report with Cakewalk

I checked the MPK225's User Guide, and it does not appear that the MIDI OUT can be configured as a THRU anyway.
 
Adam, did you try adding LoopBE1 to your system? I'm pretty sure that will take care of the problem. I was never able to reproduce this until user Silktone determined that it only affects systems with less than 2 MIDI IN port drivers (i.e. it's also a problem on systems with no MIDI IN).
 
I can only reproduce it if I disable 7 of the 8 ports on my MOTU in MIDI Devices.
 
 

What happens if the Enable Midi Out check is removed?
 
Bob Bone
 

robert_e_bone
What happens if the Enable Midi Out check is removed?
 
Bob Bone
 

then everything is fine.  but I need to keep "Enable Midi Out" checked as it is triggering something else.
 
Also "Enable Midi Out" is on by default when inserting synths (even if you uncheck the option, yet another bug).