SUMMARY
After powering up the PC a few minutes later my HDMI audio device turns off. It is displayed in system settings>audio>advanced tab with the profile set to off in the dropdown menu with no "on" selection displayed. Needless to say no sound output is produced. Restarting the computer always returns the audio device for a few minutes and if a movie is played sound is produced for the length of the movie before the device disappears again.


Syslog produces:
pulseaudio[2564]: GetManagedObjects() failed: org.freedesktop.DBus.Error.NoReply: Did not receive a reply. Possible causes include: the remote application did not send a reply, the message bus security policy blocked the reply, the reply timeout expired, or the network connection was broken.

or a similar message that includes, GetManagedObjects() failed

There is no output to kernel log

STEPS TO REPRODUCE
1. Power on or restart the PC
2. 
3. 

OBSERVED RESULT
With no action the audio device just stops being detected.

EXPECTED RESULT
The audio device is always present and available to play sound

SOFTWARE/OS VERSIONS
Windows: 
macOS: 
Linux/KDE Plasma: 
(available in About System)
KDE Plasma Version: 5.18.5
KDE Frameworks Version: 5.68.0
Qt Version: 5.12.8

ADDITIONAL INFORMATION