How do I disable Cloud Music Library sync in Apple Music for Windows?

Apple Music for Windows (AM4W) seems to have imported my local library without any issues, but when I logged in with my Apple ID it kicked off a Cloud Music Library sync and wouldn't let me stop it or disable it; the "Sync library" setting under Settings > General is set to On with the control disabled, and when I tried to close AM4W it gave me an "Upload to Cloud Music Library in Progress" dialog with "Don't Quit" as the only available option. Killing the process and restarting AM4W still leaves me with "Sync library" permanently enabled...the only way to prevent the sync is to log out of my Apple ID in the app, which hides the option completely, and also means I can't buy/download anything from the iTunes store. How do I keep AM4W from trying to sync my local library to the cloud?