Okay, all. For what it’s worth, I uninstalled the latest version of PMS and found v1.22.1.4228. After reinstalling this and refreshing music library metadata, Mood, Styles, and Genres are getting repopulated.
I forgot to take a lesson from the world of I.T.: NEVER auto-update. Download the updates, store them, and wait a week or two until you’re sure you don’t hear any screaming. 
Thanks for the guidance, @BigWheel!
