Audio mutes on when HDMI is plugged


I have a 7" screen that connects via HDMI to raspberry.
But when I connect the HDMI cable to the raspberry, the DAC mutes…

One thing I tryed was changing “hdmi_drive” to 1 in /boot/config.txt, with no effect

Can any one help ?

Volumio Information

Volumio Version:2.777
Hardware: Raspberry pi 3
DAC:HiFiBerry DAC Plus

Look in Settings, Playback Options, Output Device.
Perhaps it’s set to the wrong output device when the HDMI connection is detected.
Set it to your HiFiBerry with the HDMI cable connected and save the config.

I did so. No result.
It appears to autoswitch audio output from one to the other, because if I unplug the hdmi cable I have audio from the DAC again

Found the problem, it’s hardware
I do not need to plug the hdmi cable for dac to get mute. If I just touch (not connect) the hdmi metal to the metal of the hdmi port on the monitor, the audio just mutes