https://www.theregister.co.uk/2019/09/13/kb4515384_audio_issues/

Microsoft seems unable to catch a break with its Windows 10 updates. No sooner than it acknowledged that its CPU usage fix borked desktop search for some, users complained that the patch has also caused audio issues.

Released on 10 September for Windows 10 1903 (aka the May 2019 Update), KB4515384 is a security update that included a fix for Cortana's CPU-munching habit. Alas, it turned out that the fix left desktop search a tad broken for some users.