I am currently experiencing the same issues. I used to be able to create a station based off of a song, artist, or a combination of both song and artist. Now Siri gives me the same response as stated in your complaint. “I cannot create a station based off of that.”
I left windows and android to come to the Apple ecosystem and have purchased a MacBook Pro, IPhone 8+, Apple Watch series 4, AirPods Pro, HomePod, IPad Air 2, and 2 Apple 4K TV’s. Everything was working well with each other, except the Apple Watch fell apart without any abuse to it, and now Siri is no longer able to function the way it used to when requesting music.
Im not sure why this feature has been removed but it’s quite frustrating. I ride a Motorcycle and am dependent on using the voice command to tune the radio to play music that I’m currently in the mood for. I hope this issue gets resolved quickly.
I tried to contact support, however the waiting period to even get someone on the phone is 2+ days. I’m ok with paying premium prices for Apple products however I do expect to have premium performance and consistent features. It’s not cool to move content from one link to another without clearly stating it in the update description or to change the name or necessary voice command from one thing to another also without stating it in the update description.
Having to learn from scratch how to navigate the GUI each time an update is pushed out is frustrating.
I’ll continue to stay with Apple for another 2 generations unless these problems persist consistently during that time frame.