There used to be a fourth command in addition to “load”, “save”, “save as default” when you saved a VST plugin preset, called something like “convert program list to VST preset”, and that was available probably with 3rd party plugins or other special cases where the plugin provided Cubase with a list of it’s proprietary format. Before you invoked this command you could, instead of seeing the VST presets in the drop down menu, you saw the internal presets of the plugin. Then you hit the button and the internal preset list was gone and you have your usual VST preset dialog. Nifty !!! 
Now I don’t see this anymore and I have a bunch of plugins with internal presets I’d like to VSTify. But don’t tell me I have to do it by hand … one … by … one ??? 
There is a preference setting or something, right?
I think this command is only available for VST2 plugins, for converting old vst2 program lists. VST3 changed the preset mechanism to vstpresets, but most third party plugins do not support those, so there is not much you can do there (except for saving them one by one as a vstpreset… 
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