navigationItem.hidesSearchBarWhenScrolling = false this worked for me too!

I contacted apple just today, they told me to go in safe mode and try it out, which I did. Then switch off and power on normally... and it works! They said that with safe mode it removes software bugs. They weren't specific but my guess is that it probably does some sort of checksum with the original software to find differences that would interfere with internal systems (such as audio). I may be wrong! But it worked anyway