I have an HP Spectre x360 13 4003dx with a dual boot (using GRUB) of Ubuntu 17.04 x64 and Windows 10 Pro x64.
On a first boot (after shutdown) either to Windows or Ubuntu the sound works on both of them , but when I restart back to GRUB and boot to a different OS (e.g Windows) the sound doesn't work then boot back to the same initial OS sound doesn't work either. bottom line if you switch OS's with GRUB it shuts down the sound.
Why? Is there a fix?