Rawtherapee (flatpak) sounds are silent

I am using Rawtherapee 5.8 (Flatpak version) on Ubuntu 18.04.
The “sounds” emitted by RT after editor processing or queue processing are not working.

Here is what I checked :
The sound tab of preferences is enabled. I tried testing the default sound options like "window-attention’ on command line (canberra-gtk-play -i window-attention). They work. Nothing wrong with OS sounds.

Also, checked the options file under ~/.var/app
That file has all sound parameters specified in the sounds tab of preferences.

Sounds were working when I was using an earlier RT version from Ubuntu repository. It looks like the problem started when I moved to the Flatpak version. Suspecting a flatpak/RT config issue due to the self-contained nature of flatpaks.

Any suggestions?

Thank you.

I am willing to bet that the flatpak doesn’t have access to play sounds… Let me check it out.

Edit: the flatpak has access to pulseaudio, do you have that installed?

Thank you. Yes, command “pulseaudio --version” yields "pulseaudio 11.1 "

Note that I have never touched any sound settings on this OS either through pulseaudio or thru alsamixer etc. A few years back I got totally confused by the pulse/alsa relationship and vowed never to touch a working config if possible …

Also installed a flatpak music player Melody just to see if a flatpak app plays music. It does.

I’ll check it out when I have a free moment