Hi keef82 and djbazztek,
That is definitely not good. I'm sorry to hear it. Do you both, by chance, use Spotify? We saw this issue pop up when Spotify enabled lock controls for mobile devices. Lock controls would allow you to be able to control your music even if your mobile device was locked. Can you try disabling this in the Spotify app and see if it helps? To do so, within the Spotify app, go to Your Library > Settings > Devices > Devices Lock Screen.