Yeah, I asked for an instrumental with clarinets, piano, upright bass, and baritone saxophone, and it was a song with cheesy lyrics about these instruments. If it doesn't understand "instrumental", it just sucks.
I'm sure it's easy to fix because in the custom mode you can put separate lyrics and style, but you can't generate lyrics based on a theme and set your own separate style yet. You can generate lyrics with ChatGPT of course.