Catalina's Music App: Maybe your app is broken, too?

After 'upgrading' to Catalina very early this morning (October 8, 0800 hours), the Activity window in the 'new' Music app says "Cloud Music Library: Gathering information about your library." The task is supposedly finished, with the blue circle closed/filled. But it never... finishes.

Also, if I try to actively play a song, I'm asked to log in to my Apple ID. Which I've done. Over and over. And I still can't actually use the app. Running on a RAM-maxed iMac, using very fast biz class broadband, so I know it's not the hardware or 'net connection.

This is the fix for iTunes? Anyone else having issues like this?