Frequent Audio loss on HDMI

I have HP x2 1030 G3:
Intel Core i5-8550U

When connected via hdmi, if I play a video on VLC or a video player; I thought it was the audio codec but suddenly I don’t have any other audio.
I have to disconnect the hdmi and reconnect it but it is random; sometimes I need to unplug et replug a few times.

Another issue, one time, I had no sound at all; my internal sound card was not detected and turning volume up and down, I get a “volume bar” labelled “Dummy volume”

sorry I am new to linux; the DE used is Gnome 42

Check the audio mixer (pavucontrol) wheter it is using HDMI or your built in audio.

In vlc if you click on audio-audio device there is an option on which audio source you want to use.