Sync not removing unchecked songs from iPhone Xs
I have an iPhone Xs running iOS 12.4.
My MacBook Pro is running OS X 10.14.5.
My iTunes version is 12.9.5.5.
I recently decided there were a bunch of songs synced to my iPhone that I didn't want on there anymore. I unchecked them in my iTunes sync. I double-checked to make sure the albums those songs are tied to were also unchecked. But, the songs are still on my iPhone.
I looked for other threads about this topic - unchecked songs not being removed when a sync is performed - but the ones I'm seeing are 5+ years old.
Is there something simple I'm overlooking?
iPhone XS