I'm writing this post about Yeelight RGBW and specifically about the music mode on your app (currently I'm using it on the Xiaomi Mi 3 the version downloaded from the Play Store, the V2.1.20).
The thing is that the music mode (apart from being hidden in the settings instead of in the bar with the rest of the modes) works perfectly and I love it. However, if you try to use it when the music is not being played with the phone's speakers, for example, with headphones or a Bluetooth speaker, the app seems not to recognise that the music is playing and it stays in that pink-reddish colour.
I was wondering if this is a documented bug and/or you're going to fix it. I'd love to use this feature with the Bluetooth speaker I have or with "headphones" to connect the phone to a real speaker (using the auxiliary port).