Share Audio won't work. Please help.

Hello,

I have an issue with my iPhone.

My brother has got a new set of PowerBeats Pro and I would like to share audio with him. I have AirPods Pro (2nd Generation) and I want to share my audio with my brother's PowerBeats Pro.

For some reason, my AirPods Pro work fine on their own. My brother doesn't own his own iPhone, iPad or Apple Watch. His PowerBeats Pro are linked to my Apple ID for he doesn't even have his own Apple ID.

I have tried to share the audio and then my iPhone suddenly sets the output device to it's own speaker and plays on not my AirPods Pro OR my brother's PowerBeats Pro, but on my iPhone speaker.

Please help me!

Thanks,

Noah