Control Change 7 is not recognized by all VST synths. Many VST synths don't recognize any CC messages.
IMO the 'GM' synths should .. but not all of them do.
Sometimes it's simply not you or your hardware, it's the people that wrote a synth with a 'GM sound set' and then called it a GM synth even though it doesn't meet many of the other standard GM specs..

Just because a VST has a GM sound set (the patches line up), it doesn't mean they support all of the GM features.


Make your sound your own!
.. I do not work here, but the benefits are still awesome