The latest issue in the growing string of problems with the Windows 10 1809 update affects devices using certain versions of Intel's display drivers. The Windows 10 October update breaks audio playback through monitors or TVs connected via versions 24.20.100.6344 and 24.20.100.6345 of Intel's display driver.
https://www.notebookcheck.net/Beleaguered-Windows-10-1809-breaks-audio-playback-for-some-Intel-display-drivers.366616.0.html