No playback with MS4

I installed MS4 on my linux machine (Kubuntu = Ubuntu 23.04 + KDE Plasma).
(Sorry for my english, I'm french.)
Hello.
I have a permanent problem: MS4 seems to conflict with any other software that produces sound.
Description: I launch MS4, I play a score, everything is OK. I stop the score. I try to listen to music on Rhythmbox, VLC, or other: impossible. I have to close MS4, and restart Rhythmbox (or whatever), and restart MS4 for it to work.
The opposite is true: if I start by listening on Rhythmbox (or other), impossible to play a score in MS4, I have to stop Rhythmbox, and restart MS4.
Looks like MS4 refuses to share the sound card with another program.
But I don't know how to fix this.
Has anyone had the same problem? (Never had this problem with MS3.)
I launched MS4 on command line, if it can help, here are 3 files which contain all that MS4 wrote:
* rapportBug-1.txt : when MS4 started.
* rapportBug-2.txt : when I tried to play a score.
* rapportBug-3.txt : when I stopped MS4.

Last precision : I have this problem since the beginning of MS, 6 months ago.
Not having found a solution, I dropped MS4, and I continued to use MS3. I ended up telling myself that by tweaking my machine, I had done things that were incompatible with MS4.
But yesterday I reinstalled everything, from scratch, and without leftovers from the previous install.
Well, it's always the same: impossible to play a score if another app is producing sound. And impossible for other apps to produce sound if MS4 is playing a score. :-( :-( :-(
Am I really the only one this is happening to? It's probably nice to be "exceptional", but this is giving me away!! ;-)
Thank you.