HDMI audio output not working

Hi!
I cannot hear any audio from my Smansung TV connected via HDMA on my HP ProBook, mounting a Ubuntu 18.04.4 LTS.

I can’t even see the audio device in the devices list. Some infos

uname -a

Linux jsbach 4.15.0-96-generic #97-Ubuntu SMP Wed Apr 1 03:25:46 UTC 2020 x86_64 x86_64 x86_64 GNU/Linux

Following this help
https://itsfoss.com/how-to-fix-no-sound-through-hdmi-in-external-monitor-in-ubuntu/
I couldn’t resolve my problem.

aplay -l

**** Lista di PLAYBACK dispositivi hardware ****
scheda 0: PCH [HDA Intel PCH], dispositivo 0: CX20724 Analog [CX20724 Analog]
Sottoperiferiche: 0/1
Sottoperiferica #0: subdevice #0

$ sudo pactl list | grep HDMI
$ sudo lsmod | grep HDMI
$

I regularly see the computer screen on my Samsung TV via HDMI but no sound at all (only the bulti-in speakers work); not even the audio output listed as sound card.
What else can I do?

Thx

https://ccm.net/forum/affich-591569-hdmi-doesnt-show-up-as-playback-optional

https://forums.linuxmint.com/viewtopic.php?t=250454

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