I created a test that successfully shows the problem. Quick setup too:
Just get this and setup one or more virtual midi devices.
http://www.tobias-erichsen.de/software/loopmidi.htmlOh then this:
http://www.midiox.com/moxdown.htm or some other virtual keyboard outside of buzz, this one works well with the above driver. You want to connect midiox event port to loopmidi driver (usually as easy as selecting the device from options --> midi devices --> midi outputs), then click the wee virtual keyboard button and you should see keyboard/midi messages going from one place to another all inside of midiyoke.
Then open this zip:
https://drive.google.com/file/d/1IyOvQFTmiqzcuY-G6dq7PIehU7EQAr3Y/view?usp=sharingInside there are a couple of free VST's, and a buzz effect, Whitenoise Harmonic Delay (cuz I couldn't find any free vst effects that take note input). You can probably throw everything into your VST folder and relaunch buzz. Worst case scenario is that you have to path to harmonic delay and reset up all the connections.
Obviously I don't have to tell you how to setup the driver that you wrote to use virtualmidi.
Basically, the midi monitor comes first and that is to check if there is incoming midi from midiyoke events. Click it to bring to focus, switch over to midiyoke and start keyjamming. You should see note data flowing in.
Then it's the working method: Click to shift focus to the midialias machine. That is hooked up to harmonic delay. With midiyoke you should be able to hear notes hitting the harmonic delay, even without buzz being in focus.
Next try to hit harmonic delay directly using the same method. You should hear no changes. Or, conversely, you have no issues and my name is mutex lockout.
Thanks for doing all this and making buzz rule for hosting VST. I am working on a guitar fx pedal / looper and the workaround does do what I need, but I imagine it's not what you intended.