After using Stylus for 10 years, the only difference I saw was that SAGE was incorporated into the standalone.
And it didn't work. So I still use the SAGE Converter app.
Maybe there are some new fx or something?

 

Does anyone have an alternative to Sage for batch conversion of an entire library all at once as opposed to doing one folder at a time? Also, my Sage Converter 1.6 (PC windows 10) no longer seems to support drag and drop. I have to select everything that I want converted. Any advice that can be offered would be most appreciated.

 

That's interesting.
Over the last several newer macOS, there is a bug developed where I have to have the SAGE app highlighted on my desktop (ie. the last thing to have been clicked on) and to drag the library folder without having clicked into its Finder window.
So you are still 'with' SAGE. Then drag and drop worked.
Plus don't forget it was always a little wonky if the dev has used over 31 characters or whatever the number is in their folder or file names.
It's like some devs have forgotten how to release a lib in multi-format for Stylus RMX, I have to do so much editing to convert and add libraries!
So sometimes SAGE won't even see what you are trying to offer it. You have to hunt down the reason within the library.
If everything is presented properly it is possible to drag a folder of folders ie. a whole library as you say, as a batch conversion of sorts.
I do not know of any other script or app that has been created for batch conversion. Sorry.