Aha! I found my first problem with the new sync. For another post, I wanted a screen capture of the KDE Partition Manager, so I launched it. It appeared dark and unresponsive. After I closed it, a password prompt appeared, which had been hidden behind it.
Remember when this used to happen with Etcher? It's exactly the same thing. If you look fast enough, you can just see the password prompt appear and then get covered up by the nonresponsive partition manager.
So, I naturally had to try it with Etcher, and to my surprise, Etcher didn't ask for my password at all. Go figure.
