Apple Music / HomePod Volume Bug & Goodnight Scene in Home Bug (iOS 15.4)

Ever since the iOS update I am having issues with Apple Music and my HomePods.

When using Apple Music with my HomePods it will no longer allow me to turn the music up in the app with the bar at the bottom as well as the buttons on the side. When you try to turn it up, it turns the volume down. Despite restarting etc it is continuing to do this. The only way that has worked is to ask Siri to turn the volume up.

On top of this, the Goodnight scene in Home no longer works when saying goodnight to Siri. I have deleted and recreated the scene etc and nothing works. I now have to say Run Goodnight or similar. I have seen others with this issue but not seen anything for Apple Music yet..