I think you mean it still plays with a VSTi in the Melody track ?
The Melody track always uses the default synth so you need to move the midi and VSTi to another track.
But in RB this wouldn't be the case so not sure whats happening ?
Maybe you could elaborate more.
Below is what I thought was the issue until I saw your whole heading.
Do you mean VSTsynthfont64 as I get that with a note stuck on ?
I tried updating
https://www.pgmusic.com/forums/ubbthreads.php?ubb=showflat&Number=525054#Post525054https://www.pgmusic.com/forums/ubbthreads.php?ubb=showflat&Number=522940#Post522940Coolsoft VirtualMIDISynth you can have 4 instances if you are running other apps at the same time.
https://coolsoft.altervista.org/en/virtualmidisynth