Boom Radio wont play on HomePod

I’m based in UK. I’ve always been able to play Boom Radio by saying ‘Siri, ask Apple Music to play Boom Radio.’ Last week it started responding: ‘I couldn’t find Boom Radio in your Apple Music library.’

What has Apple changed? I’ve tried all sorts of verbal combinations such as dropping the ‘Ask Apple Music’ part and ‘Play the radio station Boom Radio’, a convoluted phrase I’ve had to use on other radio stations. I’m on the point of reverting to an Alexa speaker because if I can’t play my favourite radio station the speaker is worthless.

I’ve also turned the Siri search off and on in the Boom app settings.