Unity 2018.2 no audio on iPhone, ok on iPad (closed/hw issue)

Hi, I am building a game with Unity 2018.2 and it works all fine on iPad but there is no audio at all on iPhone.
The iPhone sound speakers works fine with any other apps and there is no error in the xcode console. Any idea how to troubleshoot this?
Thanks
Will

Facepalm… it was actually a broken mute button on the iPhone. Oddly some apps ignore the mute status. After activating the assistive on-screen mute button I could switch off the mute button and soundsou now okay in the game.
Thread to be close/deleted