We are aware of a bug in the development platform that disables/reduces the volume of music or podcast apps. This issue occurs even when Pokémon GO's music and sound is disabled in the Settings menu.
While we work to resolve this issue, we have identified a workaround to this issue.
- Open your music app and play music.
- Open the Pokémon GO app. The music will either pause or reduce in volume.
- Try to pause and play the music without leaving the Pokémon GO app.