Can Music Mode only work on one RGB Lightstrip at once?

Music Mode keeps failing and only working on one of them. I uninstalled and re-installed and the only one that works is the first one I hit Music Mode for. If I try hitting Music Mode for the second one it won’t work. Can someone give me a fix?

You can set music for a group. (Create a group for the two devices.)

How do I set up a group for the two devices? Can you please show me how to do this?

Please use Yeelight application, in the page of adding new devices.