iTunes Misbehaving After Split to Two Apple IDs

I recently split my wife and I's activities between two Apple IDs from a shared one -- I took the new ID, she retained the previous one. Since then iTunes has begun behaving in odd ways:

- Smart playlists keep duplicating

- In a series of "Best of..."-labelled Smart Playlists in which I place each year's highest-rated songs, iTunes has magically created a "Best of 2016" Smart Playlist, each of which is a duplicate of each previous year's "Best of..." Smart Playlist

- Star ratings for individual songs have been transferred to the entire album from which those tracks come, meaning my "Best of..." Playlists now contain every song on an album that contained a high-rated song.

- My iPhone won't sync new songs and albums placed onto my Mac-based iTunes library

I am running iTunes Match and iCloud Music Library on two iPhones, an iPad and a MacBook Pro, sharing the same data library based on an iMac.