Does it have an option to refresh the contents of the browser or similar, that's all I have to do in Studio One when it happens, it's usually with PA Plugins. Perhaps you have to chase them down and load them manually, I have heard this having to be done before.

I don't know what OS you use, but on Windows the presets are at

Documents/VST3 Presets/Plugin Alliance/Black Box Analog Design HG-Q

so if you are on a Mac maybe find the equivalent of that.