I didn't realise 64bit was an issue for midi data, I guess Midi is not the concern, just the plug-in itself.
Seems you are right, found an alternate way to apply midi fx and change gradually does work.
Select clip> Process> Apply Effect> Midi Effect = Doesn't work, as it wants to apply an effect in the bin, which you can't set up.
Select clip> Left Click> Process Effect> Midi Effect> Cakewalk FX> Velocity> select Change or Gradually = Does work
The chord generator from the site that had the MidiCurve is great, so simple and intuitive.