Ubuntu MATE 19.04 Final release and HDMI

Hi,

I tried Ubuntu MATE 19.04 Final release from live CD and found it cannot output sound to my TV via HDMI.

  • the videos are shown on TV, but
  • the sound are still coming from my laptop
  • when viewing the sound devices, only built-in sound device are found/listed, no HDMI sound device found/listed.

How can I fix the problem?

Note that previous iterations of Ubuntu MATE worked well, and if I switch back to 18.04, then everything is fine again.