Cantabile Lite - VST3 plugins don't save settings but VST versions DO

A user reported that their VST host (Cantabile Lite) does not save our VST3 plugin parameter settings - but the VST2 versions do save.

I’d never heard of “Cantabile” but I downloaded the app to check it out and can confirm what the user is reporting. The VST2 version works - the VST3 does not. Re-opening a saved file loads the default values in the VST3 plugin.

Now, our plugins have been working for YEARS in other DAWs (Cubase, Reaper, Ableton, Fl Studio) without any reported issues - why would it NOT work in this one obscure host? MeanwhiIe, I tested other developer’s VST3 plugins in Cantabile and they do work so it seems there is something wrong with our plugins - at least in this particular app.

Any ideas where to look? At what point in plugin construction do the saved settings get loaded? I’m not seeing it in debugger (maybe because it’s not running?).