Iíve just solved my problem of no sound via HDMI on Windows 10 on an Acer E5-571 laptop.

On several previous occasions I had tried reinstalling Intel (R) HD Graphics Famly without it solving the problem.

This time I (re)installed the Intel Chipset Driver first and then reinstalled Intel (R) HD Graphics Famly and the cause of the trouble (Microsoftís HD Audio Device) had disappeared and my TV showed up as a device for audio playback with sound on the HDMI connection.