Siri can't play albums & playlists while connected via CarPlay

When my iPhone is connected my car via CarPlay, if I say "Siri, play album [x]" or "Siri, play playlist [x]", she'll respond: "Apple Music can't play that album/playlist." (Those aren't exact words of Siri's error message, but they're close.)

This error occurs only when I'm using CarPlay. Any other time I'm using my iPhone and ask Siri to play an album or playlist from my music library, she'll play it without issue.

Also, while connected via CarPlay, Siri can usually execute a voice command to play an individual song from my music library. It's only albums and playlists she can't play.

When I get the error, she specifically says "Apple Music" can't play the album/playlist. It's not clear whether she's referring to Apple Music the streaming service or the iPhone's native Music app.

If she means the streaming service, that might explain the problem. I don't subscribe to the streaming service. All of the music in my library is local, meaning the files are on the device. They were either purchased and downloaded from the iTunes store or ripped from a CD and transferred to the iPhone via the iTunes for PC app. (Before anyone asks, yes, all of the files are imported into the iPhone's native Music app library, not some third-party media app.)

If Siri is failing to look for local music and mistakenly thinks I'm asking her to stream, that presents two questions. One, why does Siri only make this mistake while in CarPlay mode? And two, is there any way for me to force her to look for local music in my library while in CarPlay, as she does any other time?

If the issue isn't caused by Siri being blind to local music when in CarPlay, then what is the cause of her inability to execute a voice command to play an album or playlist from my music library?