@d-healey You won't believe this. I simply deleted the Oscillator1L (waveform generator) and added a new one with the same name, and now it works great! I'm afraid it was really some kind of bug.
I'm sorry form making you loosing your time with this
thank you!

@ulrik This is super useful! Thanks.

Anyone please note the combo box will have to have "saveInPreset" switched OFF,
otherwise there's a loop loading the preset as onPresetsControl fires every time a preset is loaded.