Maybe a bug in a beta release...? [ using v2.0.10a ]
Modified 'simple synth' example plus a note in the score:
f1 0 1024 10 1
i1 5 1 110 0.5
This works if I'm not doodling on the virtual keyboard when that first note comes in.
If I am, there's a continuing higher-pitched 'a' that won't quit.