I don't have any other DAWs so I can't say whether it works or not on others.
But in Reaper, when I load up Augmented Strings, the VST does load, in that I can play notes, and I can use reaper's own UI to adjust parameters in the VST. But the VST's own graphical UI doesn't appear.
When I run Augmented Strings as a standalone app, it works correctly! Just not in Reaper.
I have completely uninstalled and reinstalled Augmented Strings, to no effect.
Augmented Voices works fine, so it's not something about that series of plugins, it seems to be specifically something going on with Augmented Strings.
Any ideas?